"Winter" semester is really "Spring" semester at most places - January to May (don't forget - NU is weird with the quarter system). Moving the Portal date is helpful to the sport of college football but more or less implausible on the academic side.
As NIL deals evolve, I think it will be important for the funders to stipulate bowl participation as part of the deal. I'd love to know how the people who paid Marvin Harrison's bills this season enjoyed watching him hang out on the sideline.
Going forward, I think the playoff teams will see less attrition and opt-outs. Then there will be 4-6 teams that were on the bubble and get excluded - we'll see attrition there as well (just like FSU this season).
For the next tier down, which will very often include Northwestern, I think the bowl system will generally continue to operate status quo, but probably with adjustments on how programs are slotted. There will be cynics who say the bowls don't matter...but I'll always be more interested in the Las Vegas Bowl when NU is playing over Michigan/Alabama.