The article does ask a good question on the sort of conundrum that could become an identity crisis thst fire emblem has rode itself into with the steady inclusion of social aspects in their games ever since Awakening.
Personally I would be in favor of keeping the model they developed in 3 houses while refining it further with the game mechanics they developed in engage. I'd also like to keep the whole marriage and matchmaker aspect that we saw in awakening and fates out unless they figure out how to tastefully weave it into the storyline.
And while it would take too much gamedev time to implement it, it would be interesting to whether or not its possible to blend and synergize the fire emblem strategy game aspect with some of the musou aspects they've been lately dabbling in. I'm thinking akin to how the Total War series handles army battles but making the choices of how to play each battle as being either classic turn-based tactical mode or going full musou hack'n'slash nonsense as options for gameplay.
I'd definitely recommend Genealogy to fans of Three Houses that can tolerate unadulterated 90s JRPG. A lot of the concepts from 3H come from Genealogy - the main characters went to a school together like in 3H, the time skip, the legendary weapons. Using a guide is perfectly acceptable since it has some stupid hidden secrets that make the game a lot easier.
I remember finding the silly princess bit in DDC kinda fun. The skeleton girl has a bunch of different forms depending on how you address the illness she has. I'd like to see the romance in FE become a little more VN'ey, if that makes sense (although, this isn't really my genre)