The more I think about it, the less I think we’ll see higher ilevels than 925 or a longer grind and stuff like that. Blizzard is concerned mostly with seasons, as that’s where they expect to make their money, and it’s in their best interest to keep an seasonal player’s ability to “top out” and experience all the same content within the same time frame as now.
That’s one reason I think we’ll see leveling speed increase again even with a possible increase in pre-paragon level cap, and possibly paragon levels as well. I DO think we will see power creep. In addition to the levels, I suspect:
Ilevel maximum will stay at 925, and masterworking will go to level 16. This will involve a mat the same color as a unique tier item, and 1-12 will be rebalanced to be the “easy” levels to get, and 13-16 will be more similar to 9-12 currently. Pits themselves will stay largely unchanged, although the tier breakpoints and neathiron boss mechs may get changed or nerfed to make them easier, in line with my previous statement.
Glyphs will go to level 25, and Nightmare dungeons will be rescaled and have a higher endpoint than 100.
Other scalable content will take the new level cap into account, and the overall scaling system will be re-done to take into account sources of power creep.
Stat squish is a non-issue; we’ll just see smaller life and damage numbers; the game will function identically since all the modifiers work off of percentages. Armor (which works as a percentage after conversion) will be squished just so it doesn’t look out of place next to the other integer numbers in the status screen, even though the actual integer range for armor really doesn’t matter.
We may see higher gem recipes as well.
If there will be a higher difficulty tier, it may be functionally the same as tier 4, just with stronger monsters. Whether or not it has a resistance penalty higher than tier 4 I think will depend on how much the sources of resistance change. If masterworking and/or gems is increased, some can come from there, but (unless this is changed also) base accessory and paragon node resistances are set at specific values. So I’m not sure about this one. I don’t really think it’s necessary to add further penalties to resistance as the methods to cap it are basically required for every class. Higher damage/higher health can be implemented without any other changes, similar to D3’s torment levels.