Glad to see someone else has played this, and enjoyed it enough to want more of it. More Suikoden love in general is always great. I know IV was 90% hated, but I'd love to see III, IV, Tactics, and V on PS4, or at least IV-V, since III only recently got released as a PS2 Classic on PS3.
This would be fantastic to see. Granted, owners of the original can use component cables and progressive scan to upscale to 720p (JP version goes to 1080p, supposedly), a proper 1080p upscale w/ trophy support would be fabulous. (And while they're at it, I don't believe the original ever got a PS1 Classic release, did it? Sure, there's Lenneth on PSP, but ports haven't stopped them with other titles...)
Now here's a series that seems to have sorely missed out on a lot of love other series have been getting these days, between HD remasters and ports. I only ever played the original, but between my own experience with that and general comments I've heard about the others, this seems like it would be a great choice to upscale and port.
As for my own choice(s), I'm not sure I want to compile a list, but a title or two off the top of my head (or, rather, off my shelf at a glance)... Some Fatal Frame love would be great, although the first three all got PS2 Classics. Front Mission 4 would be great as a Classic or otherwise, and maybe they could even look into finally releasing FM5 in the west via this method? (Others, too. Would be cool to see it used as an excuse to finally localize various titles.) Legaia 2: Duel Saga, perhaps? I would say the Mana Khemia games, but they had pretty poor graphics even for their time, so I can't imagine HD upscales would be in high demand.