To me what makes SFAM a strong, cohesive album is the way the album is unified musically, not lyrically. I don't think the "concept" is that good either, and I couldn't really care less about lyrics, so that aspect isn't what enhances the experience for me. I don't think anyone likes SFAM primarily for its story/concept.
It's the musical side that enhances it. Musically, I don't think any other DT album kicks off better, with Regression > Overture > Strange Deja Vu > TMW > FT etc. Then there are the recurring themes throughout the album, and the Metropolis references. It ties together as an album. The lyrics could be about breakfast cereals for all I'd care!
It's that unified listening experience, and the way the album is greater than the sum of its parts, that makes people want another concept album, I think.
I think starting off with an "opener" that is more of an introduction to set the tone is a good way to help shape an "album" as opposed to merely a collection of songs. There are many other ways to help unify an album too, without needing to be a concept album. Just look at Awake, and the way it reuses little themes here and there. And despite not being one of DT's stronger albums, the way they unified Octavarium was a great idea too.
I don't want them to force another concept album. They should only do it if they have a great idea first, rather than just deciding "let's make another concept album" for the sake of it.