I doubt Falcom will be abandoning the PC platform anytime soon. If anything, I can see them releasing the game simultaneously on PC and PSP... but even that's unlikely, I think.
Yeah, that's what I want to think (especially as Falcom themselves haven't released a recent Ys game on PSP yet)... but I can't explain why they'd be making a big announcement in a Playstation-centric magazine if it's coming out PC only.
[EDIT: Actually, scrap the above. One of the latest posts on 2ch points out that it was actually Dengeki Playstation that first ran a huge feature on Ys 6 (the PC version). That's... strange, but reassuring nonetheless.]
news.dengeki.com/elem/000/000/144/144364/ "According to a Falcom staff member, the protagonist [of Ys 7] will be Adol and the story will be 'the five great dragons of Altago.' More details will be introduced in the next issue of Dengeki Playstation, out 27th March."
The five great dragons of Altago for Ys 7? Wow. If the rumour is true, then we'll finally get to see the last one of Adol's three great adventures. I thought Falcom would release the definite version of Ys 4 before working on it but oh well. I can't wait for March 27th to come by.