Ferrari are a one driver team. The second seat is a support role. When Montezemolo said Perez 'doesn't have enough experience', he forgot to finish the sentence. He meant doesn't have enough experience in playing a support role. This is why I believe Perez would only go to Ferrari if Alonso leaves.
The options are :
o Schumacher to retire at the end of this year - he came back to enjoy himself... and he was until this year when lady luck dealt him an atrocious hand.
o diResta to partner Rosberg at Mercedes.
o Hamilton to stay with McLaren.
o Perez to stay at Sauber.
o Massa possibly to Force India [with a swag bag]... or maybe to retire.
o Webber to go to Ferrari.
o Ricciardo to go to Red Bull.