One change that I noticed during the course of the 3e, and continuing into 4e was the expectation that a fighter would have an 18 strength, a wizard would have an 18 intelligence, etc., as starting characters. It's not an absolute, by any means, but it certainly doesn't seem to be remarkable to see multiple 18s in one party. I know my group has seen a bit of escalation, in this area, over the years. In AD&D, we typically felt pretty good about a 16 in the prime requisite stat, saw a number of 15s, and either rejoiced at our luck (if using dice) or made sacrifices (point buy) when we had an 18.
In 3e, we slowly went from 28 point buy as standard, with 32 for special circumstances, to 32 as standard, with 36 as special. Part of the reason, I think, is because we'd start a new campaign after playing the last set of characters up to level 10-15, so the starting stats looked a bit lackluster. When 4e showed up with the higher racial mods, it just about made my head pop, but it also made me realize just how high our stats had gotten.
Personally, I hope "flatter math" includes "flatter stats", too. I don't want to see the range change, and I'm okay with the modifiers. But, if the system performs very well at lower stats, I'll be quite pleased. Hopefully, an 18 can feel like something special, again.