Given that the Persona series is connected in the sense of being a series of stories largely in the same universe, but not always with the same characters or reasons things are happening, there is no reason it cannot continue, provided of course that the writers can come up with material. One of the reasons why - just for example - Final Fantasy worked the way it did was that it's a different world with different people and problems, a new plot instead of an addition to the plot that happened before-then. Now, this isn't a perfect method but Persona's way of doing things is similar.
Persona games are relateable, in that it's always our world that this is happening in. It's Earth in a modern period. We don't need to learn as much about the world it's in because we understand it. This is different from Shin Megami Tensei: Nocturne, where the world has ended and this is what comes after. (SMT: Nocturne is a really great game, though, so play it if you're up to a severe RPG challenge.) The first three Persona games (The first one and BOTH seconds) are highly-connected in story and in the same world, though Persona 3 and up have been still in the same world, but not the same story. Whether the Shadow-related games are going to come to a convergence point or not has yet to be seen, but you see that these formulas work.
Really, when you consider that Shin Megami Tensei, Persona, Digital Devil Saga, and Soul Hackers - Their most-complicated stuff. - have done very well and show how much creative power they have over their corner, the people who work on those things would be the sort of group worthy of continual production of their product over a long period of time. It'd be worth doing.