Parker is going to remain, Leonard is going to continue to take on more of a featured role and obviously Aldridge immediately would, if he's signed. Clearly, they'll need to replace Ginobili's role. It could be a combination of Anderson/Joseph, it could be them taking a flier on Shved, or in a year circling back to Turner (not a fan, but they were rumored interested at the '14 trade deadline and they could only afford him if they don't sign Aldridge), etc. Also keep in mind, they won't need as much play making as Ginobili has provided in recent years with more legitimate featured scorers.
Green is valuable irrespective of their declines. In fact, he just had his best season in spite of it.
It's much more difficult to find than you realize. Only in the past few months has Carroll went from a guy who could make threes to a legitimate three point shooter. Even now, he's not the feared shooter Green is. Franklin can't shoot threes. It's possible he could be the SG version of Carroll in two years, but this is a team trying to remain contenders in the interim; they can't be taking massive risks like that.