I guess, regarding types of units and towers being used in high / top lvl bases there’s indeed a little more variety than a year ago.
Though, a year ago there weren’t even dungeons/monsters (or maybe they were, but let’s say 14 months ago they weren’t… anyway, I guess you get what I want to say), so more troop types are available now, so the % of useful units didn’t really increase. For obstacles it did increase (boosted barricade and boosted trap now, compared to only blockade before), and for towers, it also increased a bit (+ boosted bomb tower, sometimes snake).
Now, while I agree that there’s lots of difference in the details (and also some non-standard designs being used), there are still some units heavily present in most/all high/top lvl bases (e.g. mummies (+ spawned knights), frosters, arbs), a few more present in some / used to fill up empty spots (archers, wolf, cannon) and quite some not used at all (pyromancer, mortar, paladin, ogre, gargoyle). So there’s still a heavy tendency to mass-use a few troop types, and quite many are ignored altogether, which leaves balancing-wise plenty of room for improvement IMHO.
Especially if e.g. the last regularly unlocked unit (mortar) isn’t used, and the 3rd-last regularly unlocked unit (pyromancer) isn’t used, the argument “nooby stuff for beginners only” (which is just an excuse for not optimal balance as well) just doesn’t fit. Beginners can’t use mortars, you unlock it at medium lvl only. By then, other troops are levelled up a lot further so the lvl 1 mortar isn’t much use yet. When you have enough gold and time to level up your mortar, you get a short time where you could effectively use it, and then this last-unlocked troop gets useless again in high lvl.
I mean, the knight (first unit available) was useless in high lvl until it got additional levels and a boost, but now the boosted knight is just as useful as many other (boosted) units - and for unboosted medium lvl bases the unboosted knight probably also is useful - now the knight is useful* from start to end, being balanced. So it should be possible to make other currently useless units useful as well.
(* still, knights, even boosted aren’t overpowered as they alone won’t win your raid, nor make you unbeatable, given you face a base that is as high lvl as your offense is)
Concerning layouts, the variety seems to have increased a little bit since introduction of 29 path tiles, but I agree with Fii, copy cats will always copy, and it will always work to copy unless flaregames completely changes the whole base building system - and I guess this won’t happen and also many players (not just copy cats) wouldn’t like it either - so it’ll be hard to tackle that issue (given it is one).
Nonetheless, base layouts will always depend on what units and towers are the most useful. The bomb tower boost with increased range together with longer paths made some more different layouts feasible, and a couple of months ago where the tanky boosted ogre boosted wolf combo was in fashion, we saw many bases with barely any path overlap, then the boosted cannon bases with maximum overlap came in fashion, then the (overpowered) arblaster basically replaced cannons for the biggest part, yielding also path-overlap heavy bases. Though, the powerful mummies being tanky melee troops made it feasible to reduce classical path overlap a bit if you want to, even if across-path long range bombers and arblasters as well as buffed / bugged (?) frosters still are favouring some kind of path overlap for at least part of your base.
So, when the balance in terms of troops and towers gets further improved with more viable options / alternatives, the amount of viable base layouts will most likely also increase, even if there will still be some standard designs as they will always exist as long as you can copy layouts from others.