Tiger Woods introduced a new generation of athletic kids to the sport of golf. Before Tiger, the bigger, more athletic kids grew up playing football, hockey, basketball, baseball, etc. from an early age through high school. Once Tiger made golf more *cool* some of those athletes took to golf instead, and we are now seeing that byproduct on Tour now. Augusta might have been "Tiger-proofing" their course but what they were inadvertently doing was proofing their course for a new generation of athlete-golfers.
There is no doubt that the average Tour player now is bigger, stronger, and has a more violent swing than just 20 years ago. To me, it seems like Golf is going the way of Tennis. Where kids are playing a hard driving (especially on joints), physical sport that used to be more about finesse and now is all about power and speed....but players are "over the hill" past 30 or 35.
A person like Jason Day doesn't strike me as having the staying power as compared to other players like Ricky Fowler or even Dustin Johnson. DJ may hit it a long way, but he isn't bulky at all...he's mostly just tall/long and very flexible. I think you have to assume issues with guys like Rory who have bulked up a frame that isn't designed for a bunch of muscle and a repetitive, hard, swing.
So, I think Jason Day might be closer to Tiger, and Ricky Fowler might be the perfect example of a modern day Langer (in 20 or 30 years).