I'd like to see lord come back. It's broad enough to be applicable anywhere. That means lords from say, Kamigawa could be reprinted in Innistrad without flavour issues. That inter-setting applicability is also essential if WOTC wants to make a lord tribal card down the line.
This.
The biggest issue I see with lord is that it was already a type once and then errata'd out of existence. If lord were brought back would
Zombie Master be a lord? The lack of a simple answer may be what kills lord's chances of returning.
There's also the issue with "lord" being slang for any creature that boosts a specific creature type. I see this as less of a problem. EDH may mean "Elder Dragon Highlander", but people don't usually get the impression you need an elder dragon to play. Not to mention, you can just call the format "commander".
I think I would just give back the Lord type to all creatures that were originally printed with it, that seems like the most consistent option. Sure, not all of them would be 'lords' in the actual in-world sense we're talking about, but even with the older Lords there are many where it still fits (either spot-on or just enough). And I think the slang term could coexist with the actual creature type, I don't think there are many situations in which it would actually lead to confusion. Just think of it as a mechanical shift from "strictly tribal support" to a broader use of the type that includes flavour-lords like actual rulers. A bit like not all Skeletons getting regeneration anymore these days (which is also due to the fact that they want to kill regeneration for good. Which is a shame, but let's not go there).
I can't see a clear best choice for categorizing peasants/ commoners/ citizens and I'm not sure one is needed.
Agreed. I think Merchant, Farmer and something like Bard or Musician would be great additions that could cover a lot of common folk, but Townsfolk and Citizen run into problems on Ravnica.
I'd like to see wolves condensed into hounds.
Please no, Wolf is just way too evocative a type to kill. I mean, sure, wolves and dogs are really close, closer than other types they condensed like Frog/Toad or Ape/Monkey, but it just takes away all the flavour points.
Merging dryad into nymph makes sense, but the word "nymph" has its own troublesomely sexual connotations. I'm not entirely sure how many people understand that dryads are nymphs either.
Wait, there are people who don't know dryads are nymphs?
Time to educate them!
I'd love to see more Nymphs in other colours, but the special status of the Dryad type would be the odd one out and kinda break the cycle every time they showed up alongside other Nymphs. I wouldn't worry too much about the sexual connotations, you can't shy away from calling a nymph a nymph just because the term has acquired other meanings over time. The type already exists in Magic anyway, and I don't think the sexual connotation is strong enough to totally warp people's perception of the cards.