1. every year new class for me 12 total to choose would be perfect.
2. I would expand paragon system, skill tree, max level.
3. add new features each season (similar like now but much more game changing).
4. drop rates tweak hell yeah! I still getting other class items... Itemization kinda broken too many unuseful items all legendary should have different affixes (gameplay changing) we salvage too many!
5. change current no! Implement new each season yes! please
So having in mind that new team for classic games involved and D3 kinda is in that category we could hope getting something new not only small changes each season but more new content just maybe this year blizzcon will give more love for Diablo!