I don't know and I don't care. All I need is split screen co-op. The genre could be a platforming FPS for all I care, but add co-op and I'm all In. It wouldnt hurt to have more game modes though, the campaigns have been novel experiences since the 1st game.
Resident Evil is similar to Final Fantasy and Silent Hill.
there are quite a few games in all of the series and all of them have sold well and a few games in each franchise are considered to be among the all time greats in gaming even those that didn't have high review scores were fairly popular with a large sement of the games so more games have been made for the current generation of systems.
I expect to see a new entry in the Resident Evil series before too long and if you are a fan of Silent Hill and Final Fantasy or even Forbidden Siren and Alan Wake each of these could very well have a new game out before too long and I would go so far as to be willing to bet on at least SH and FF.
and I would not bet against any of them.
there also are many more games that have been popular and deserve sequels.
too many to list them all so we can only speculate on which sequel will come out next