He has always looked fragile ' e.  to me .   At the age he ll come back   he ll likely get hurt again and something totally different .  
Starting over might be a big mistake at another team .   He know how hard it is to lead a team ,  it won't be any easier as he gets older and he may not have a good coach or support he has in GS. 
If i was him i d just fade out with Klay and Steph at GS and then hang em up.