I don't see the college schedule as a reason for Makar to leave. 35-40 games is enough and hasn't hurt many players who have gone the college route. The time off isn't just about strength training either... there is more coaching and film study going on too. There are pros and cons to all things, and staying in college isn't all rainbows and unicorns (neither is going pro)... but I do think there is something to stability and figuring out how best to apply his talents on a consistent basis. Makar was the most talented player on his team by far, but it is really hard to argue that he was the best player on the team. To me, giving him another year to really figure out how to dominate college hockey would be hugely beneficial. Much more so than him trying to figure out how to apply his talents at a higher level for the 2nd straight year (and considering the large jumps between levels... seems aggressive).
On top of that, there is still a solid chance he'd be playing pro at the end of the season anyway. I think UMass will be a solid team with him (I think they will have a really solid chance at being in the tournament), but if they aren't... Makar is playing pro hockey in March. To the tune of a 10-15 games with the Avs.