It really comes down to what SE might feel will make them the best profit. In the past, a remake on the DS was the most plausible but the PSP has finally started to catch up in recent years. Throw in the fact that many fans want to see it on a stronger system and SE has a few things to consider before they give it the go ahead. The same really goes for FFV as well.

I would personally like to see it on a console, its not that I dislike the handhelds, but I feel the games deserve complete remakes with SE using the best of their abilites on the best hardware. I don't think VII fans would be too thrilled if VII was going to finally be remade by Matrix on the DS or have a pseudo-remake like Chrono Trigger on the PSP. Most VII fans want a PS3 remake, and I feel V and VI fans would want the same. Throw in the fact that the games are better balanced and have more that can be done from a technological POV for their stories and I feel V and VI could do stronger as console remakes rather than handhelds.

I don't mean to bash Matrix cause they have done amazing work with III and IV but I also feel they are close to pushing the DS to its limits. I can't see them creating something better on a consistent basis for the DS hardware. The PSP is a better option but I still would prefer a console if we are going to even bother. Its my problem with the PSP, if you choose it cause it has the better hardware, I feel you might as well just take the leap and move it to console. Crisis Core and Dissidia didn't really benefit greatly for being on the PSP imo.