I found out too that when the PGWP expires, and you apply to get it extended, you will get implied status which allows you to continue working. But when the refusal comes from CIC Vegreville ( work permit extension for PGWP will definitely be refused), you will be out of status, then you have to reapply to restore your status. During this time you can not work while the restoration is being processed. Maybe research more on this, that's all I know.
Yes, if the nomination does come, then you are safe. I spoke to one of the Managers before May 1st changes, and they changed their way of thinking as far as nominating someone earlier just because the work permit is expiring. They didn't seem to care anymore because he said it is the student's responsibility to have legal status and to not put the obligation on SINP to give them their nomination. Now we know what transpired after that, they closed applications for out of town students and have allocated the certificates to SK students only; although students who have gotten a file number before May 1st are included in the inventory.
Students like me and others that have arrived in SK early to do the work experience time and got settled here lost our early nomination to students who have arrived much, much later in SK and whose permits are expiring earlier than ours. Not to blame anyone, it seems SINP now have better efficiency and control of the situation.