GO bus traffic downtown is anticipated to drop a lot as GO expansion comes online - it already has much lower bus volumes into Downtown than it did a decade ago despite your assertions. As off-peak GO services increase there will be relatively few GO bus services into downtown. The Milton line is the only line with replacement bus service with no real plans for off-peak services.
Well again, that's going off of Metrolinx' "promises" of GO Expansion.
We've seen it with them time and time again, they promise one thing and a whole other thing unfolds. GO Electrification is so down in the future, and the scope keeps getting watered down. We really dont know when expansion will unfold, especially when there are so many promised projects which Metrolinx havent been completed, and there are no solid timelines on when they will be completed.
We'e been promised off-peak service for many lines (ie: Kitchener) and while that has gotten underway, it's still languishing behind and no where near frequent enough.
GO bus volumes to Union have been reduced because:
a) Metrolinx shifted some routes to no longer serve Union Station, due to the Gardiner congestion screwing up travel times so badly on routes
b) the GO bus fleet being constrained and they werent able to add capacity to many routes which are/were in desperate need of increased service. The recent order of buses will help alleviate that constraint, so bus service on many routes can now be increased.
Intercity bus demand has increased, and continues to increase. Various operators in an ideal world are looking to increase service to Union. The reason they cant/dont bolster their service as much as they would like is because of: a) slot restrictions and, b) the insane travel times into the downtown core.
For GO buses to get downtown, they have to fight their way along either DVP or Gardiner. Is there merit in having some routes serve Don Mills-Eglinton Ontario Line station once that is online, to take pressure off the downtown terminal?
Don Valley station isnt able to accommodate GO buses unfortunately, and Metrolinx has a phobia of providing services in Toronto where it's seen as a "duplicate" to the TTC.
I've sent notes to them countless times asking for why certain routes dont service places like Yorkdale, Kipling, and York Mills. And it's always one contradicting BS answer after another. Sometimes they dont want buses to get caught up in traffic, other times there's already a "parallel service" in place offered by the TTC.