Personally, if I was booking YYZ for the summer in the next few weeks I'd either book Affair or look at other scheduled carriers via LHR, AMS, CDG etc.
As said above, AC apply every year so until it's announced I wouldn't hold off on anything. Having said that, the system is not usually updated with AC schedules so I suppose we await an announcement! It would fit in if LH and Star are focusing on MAN as a UK gateway.
Surely the extra 3" can't stop you booking with another carrier? Although 35" is fantastic for Y, if TOM don't operate 32" is the best you're going to get with any carrier!
Unless TOM look Canada's way...