Ferrari's driver philosophy was, is and has always been for a driver to have to prove himself at another team to be a very fast, and very capable driver, then Ferrari will swoop them up, and/or they will want to hop on the Ferrari bandwagon.
Massa did it by being pretty quick in the Sauber, just like Perez is now, but the thing is, Perez has been in F1 for one year so far. Massa was at Sauber for 4 years and was Ferrari's test driver for 2003. That's a long time. Perez may find himself in a seat in the future, but it will take him at least another year of impressive results, and it would mean he'd have to get the better of Kobayashi as well, before Ferrari consider it. Not only that, but Massa would have to continue his string of bad results, for that second seat to be opened up. Even then, Perez may face competition from other drivers for that seat.
Ferrari is Ferrari, they can get any driver they want, really. I'm willing to bet my house that Ferrari buys Vettel out of his contract with Red Bull in the next few years. If Ferrari called me on the phone asking me to drive for them, i'd have sold my house for a plane ticket to Maranello already.
I don't. As much as I'd like to see Senna with a seat...there are much better drivers available and I'd rather see Williams succeed again (one day). I'd rather have seen Alguesuari or Buemi with the seat. I don't really care for Petrov or Sutil so much but they would also be perhaps better choices than Maldonado or Senna.
I hope very much that if it is true that Williams have a highly successful season and that Senna finally shows that form he has shown on a more consistent basis and builds a strong F1 career.
But I doubt it will happen.
To be honest, I would rather see Barrichello make a 20th season. One for the records, and two because I believe he is far more useful to Williams for developing the car than anyone else as well as providing a good base for solid and consistent results. Not to mention that Rubens Barrichello deserves a proper send-off.
We don't know if this rumor is even true as yet, but if it is, you can expect that Rubens probably retired, failed to secure enough sponsorship, Bruno brought more money to the table, or all three of those things. What Rubens brings in experience, Senna may bring back to the team with money. Plus, being a Lotus test driver for a year, means he might have some knowledge about the car, that could help Williams develop theirs. Or so i'd hope.
Anyway, my driver has found a seat, so i'll wish that Petrov himself does indeed find a seat as well. Good driver, deserves another year to improve.