While a novel idea there's, unfortunately, some things to take into account.
First off, Phantasy Star Universe is an online game with servers on similar scope as PSO2. While the game does have an Offline Story Mode, that would only encompass Episode 1 while Episode 2 and 3 would be unavailable or at worst, feeling barebones made into a Single Player game. "Bring back the servers right?", Online Games carry a risk since they need to be actively making money to keep their servers up so they need to be able to appeal to the casual players as well and not just the nostalgia crowd. Blizzard was able to do this due to just how big they are globally and how much money they keep making, same goes for Square Enix and Final Fantasy XI. In comparison... PSOBB had to close since SEGA could not manage two Online based games at once and to make matters worse they weren't making much money on it due to the game being old at that point. While Phantasy Star Universe has aged better, it still has some elements that might be rough around the edges at best.
Now, Phantasy Star Portable 1 and 2.... Portable 1 definitely has a chance due to its original release not having Online play at all bt... given that in a potential collection people would want to play PSU and PS Portable 2 online, it would feel awkward not to include Online play...
Portable 2 (or in this case, I'd recommend they use PS Portable 2 Infinity which has all the content from PS Portable 2 and more) while not Online based, did have it as one of its main appeals be its online multiplayer. However, if they made use of Sony's PSN servers as opposed to using a custom server software which they host themselves they could substitute this with the platform-specific servers (e.g Xbox Live, Steamworks, these are very basic servers though that are mainly peer-to-peer so while perfect for something like PS Portable and Portable 2, its not recommended for PSU which has a lot of server-side stuff (characters, storage, etc) and has areas with lots of players (the lobby)).
These are things to be taken into account and a reason why the classic series can get collections and rereleases but not the Online focused titles...