I understand that ( this intent to reside ) clause is repelled from the Fall with the Bill-6 right? So does that mean one can leave the country after applying ( when Bill 6 is the law from this fall)?
The intent to reside provision was repealed as of June 19, 2017. While this was part of Bill C-6, it is the part that took effect when the Bill obtained Royal Assent. Note, for example, that the former item 10 in the previous version (10-2016) of the application does not exist in the current 06-2017 application. That was the item which required applicants to declare their intention to continue residing in Canada if granted citizenship. (3/5 rule and other parts of Bill C-6 are planned for implementation in the "fall.")
Even when the intent requirement applied, there was no restriction on applicant's travel abroad.
Leaving the country to travel is one thing, of course, and moving abroad is quite another. There are many reasons why the latter could raise issues and, potentially, cause problems. That said, there is no prohibition. Living abroad after applying does not directly disqualify an applicant. Still not a good idea for someone trying to become a citizen, but that is more about practical reasons which have been discussed at length in several topics.
One of the issues, of course, has to do with the applicant's obligation to keep IRCC informed if any information in the application changes. Current address is actually one of the few items of information in the application which can change. My guess is that but for making a misrepresentation by omission, that is not properly giving IRCC notice of the change in address, and getting away with that (not recommended, by the way, and actually the contrary, this is NOT the way to do things), moving abroad while the application is pending will seriously risk practical problems tending to derail the application. Some will succeed, quite likely, though some of those will have made misrepresentations to IRCC of one sort or another, and again that is not a good idea.