I'd be shocked if Go North East did decide that "Drifter" 60 required a smaller vehicle seating capacity than it does at present.
Two years ago or so, I remember while travelling to school on a morning, about seven buses (3x Drifter 60, 2x Drifter 61, 2x SimpliCity 42) drove past me because they were all full. This happened on a snowy morning, and the heaving passenger numbers continued well into the morning.
I was ill, and actually had to be sent home from school because I was that bad. All through being in the cold for over an hour because of passenger numbers being so high on the bus services I'd usually use to get to school.

During the day, it's not half as bad, I agree... But no. It just couldn't happen for schools.
During school time kick-out of arrival times, the 60 requires double deckers nevermind StreetLites.

I use the 60 on an almost daily basis still (as well as the 61/42), and nothing has changed.
I also use the 39 regularly (hence why I suggested vehicles with a higher seating capacity than an MPD previously), and it doesn't require a larger vehicle than a 60.