I'd be quite happy if we get Oath of the Ancients paladin and Pact of the Archfey warlock. Really increase the range of nature themed classes so I can play more of a variety beyond ranger/druid.
For druid I am pretty confident we'll get Moon and Land, so I am hoping we at least get Shepherd as well since that gives a nice variety in druid playstyles.
For ranger I am hoping we see Gloomstalker, Horizon Walker, and Monster Slayer. I loved all those sub-classes, though Larian will have to be careful since re-doing core ranger might lead to power creep with such strong sub-classes that were designed to compensate for core ranger being so disappointing in 5e.