Current stuff up till whatever they have planned till 2.2 and 2.3 is fine and will work on the PS3.

However, if they added new contents which has more UI, PC can handle it fine without a problem but they have to make it work on the PS3 as well, if the PS3 version can't get the UI working due to the amount of memory already used up on the UI they can't do it, thus pulling PC version from also having that content since the PS3 can't do it.

BUT, they have enough room planned for the alliance UI so when some UI's are not being used on that specific content, they can use that memory space to bring in the new content UI, so all-in-all it's still possible. It's just going to be harder for the devs to decide to how to get the content and UI's working. Only PS3 pulling PC versions leg might be the part it's going to take that much longer to get anything new out, since they have to make sure it works on all platform. Once the PS4 comes to play that another workload for them also (which I assume is easier than PS3 vs PC workload).