You do have some great points, and I want to add some more. We actually do have some reliable stats to do a guesstimation:
HERE
Basically, IRCC has granted 42,642 PRs for the Economic stream off the 160,600 quota in the first three months of 2016. I'd say we will have the same number from March to present, so it would be another ~40,000. Therefore, we have around 80,000 ITAs left for this year which will be divided between multiple streams, including backlogs, Express Entry, Live-in caregivers, caregivers, Investor skilled trades and PNPs.