I stand corrected, as indeed the detailed platform (more extensive and detailed than what has been summarized in stump speeches and media coverage) does include a commitment to restore credit to students and other temporary residents. Details of this are not specified.
The platform also states, even more generally that the Liberals will repeal the unfair elements of Bill C-24 "that make it more difficult for hard-working immigrants to become Canadian citizens." Not sure what this means.
The details in the Liberal platform regarding immigration are found in a pdf at https://www.liberal.ca/files/2015/09/A-new-plan-for-Canadian-immigration-and-economic-opportunity.pdf
The other high profile commitments for change include:
-- repeal the so-called "two-tiered" citizenship provisions in Bill C-24
-- increase budgets for processing applications in key areas such as family class reunification applications
-- expanding program for accepting refugees in Canada and funding refugee aid programs abroad
In so far as restoring credit for time spent residing in Canada before becoming a PR, it is difficult to see how that would work without some major changes to the Bill C-24 physical presence requirements, the 4/6 rule. The question then is whether this is a commitment that will be kept or whether even the 4/6 rule might be rolled back.
As others have noted, there are two other big factors. One is the timeline. The Conservatives, for example, had been promising changing the residency requirements to become a citizen back well before they formed a majority government in 2011 (and had tabled bills to do so but did not get them passed before Parliament was dissolved), and the changes which just took effect in June 2015 were promised in the 2011 campaign. Changing the law takes time.
The other is just how difficult it is to make changes like this. I already alluded to the problem in restoring the credit for pre-landing time is that it is hard to see how that could practically be implemented without changing the 4/6 rule as well. The 4/6 rule, however, is tangled with the 183 days X 4 years rule, and the 4 X compliance with tax filing obligation rule. It seems unlikely that all this would be dropped and the requirements return to as they were. Especially when these changes were almost certainly applauded by most Canadians. In other words, stepping back the requirements for citizenship will be no easy task, and not one to be done soon.
That said, repealing the so-called two-tiered citizenship provisions does appear to be a priority, and in his victory speech Trudeau alluded to this in restating a common refrain of his, "a Canadian is a Canadian is a Canadian." And if a bill is tabled to amend the Citizenship Act (to repeal provisions adopted in Bill C-24), it seems likely that at least most changes to be made would be included in that tabled legislation.
Hard to guess how soon or how committed to actually following through on this Trudeau's government will be. As I noted, it is not as if this aspect of immigration and citizenship, the requirements for becoming a citizen, got much attention at all (particularly as compared to the attention given the provisions for revoking citizenship based on certain criminal convictions, the so-called two-tiered citizenship provisions).
Campaign promises and reality:
It may be worth keeping in mind that this platform was drafted before the Liberals were really a contender to form even a minority government. It was barely two weeks ago when the majority word even came up regarding the Liberal's prospects, and it was laughingly dismissed. Well into the day Monday, election day, pundits and pollsters alike, in unison, were still quite emphatically predicting NO majority government. It is somewhat easy to make very broad, sweeping promises when there is no prospect of having a majority government. Elizabeth May and Gilles Duceppe, for example, could freely make wild promises because there was never any chance of them forming a government, let alone a majority. The three major parties needed to be somewhat more tempered in their promises, just in terms of being somewhat realistic, but throughout the campaign it was clear that both the NDP and Liberals were making the broad sweeping promises of a Party aiming to win enough votes to win enough ridings to become the government but with little or no prospect of forming a majority government.
I do not know of a single pundit or pollster who forecast any party having a chance to win more than 155 or so seats, 162 at the very most, and only then if there was in effect a huge tide late in the race. There was a huge tide late in the race, a far bigger tide than any of the pundits, pollsters, or even party insiders so much as imagined.
That was the long way around to saying that the Liberal platform was drafted in a context which had very low prospects of being in a position to actually follow through on all the commitments being made, in a context where even a big win would not give them a majority, so that the actual changes would be only those agreed upon by multiple parties. I can imagine some Trudeau insiders already biting their lips, wondering oh no, what do we do now . . . all those promises . . .
I certainly do not expect them to follow through, certainly not completely, with every promise. And it is the bigger, broader promises I am hoping Trudeau works hard to keep the most, like listening to every member of Parliament in the process of making decisions (Harper did not so much as even consult his own caucus, let alone non-Conservatives). That, however, will be difficult at times, inconvenient, and slow the process down. That's the hard side of democracy, the side of democracy Harper was never willing to engage in, let alone work through. And of course if Trudeau lives up to this campaign promise, that will mean he will not be able to follow through on many, many of his more specific promises. That's OK.
In any event, for PRs who do not qualify for citizenship under the current requirements, but who would sooner qualify with credit for time in Canada on a student or work permit, probably better to not get your hopes up too much that change will come soon enough to make much of a difference for you personally. Maybe it will come, and come in time to work for some, but for most of those it would benefit if in place now, that time period will be too far back to help by the time such changes are actually made and implemented, even if the timeline to making the changes is as accelerated as could conceivably be.