Regarding The Final Season Of "Friends"?

OK, so I'm a huge "Friends" fan and have seen almost every episode. My favorite season is Season 10 because that's where Joey speaks French, Ross gets a tan (and another one and another one...), Phoebe gets married, and Chandler and Monica end up with twins.

I have read that Season 9 was supposed to be the show's last (it obviously wasn't) and that, after Season 10, if the actors wanted an 11th season, David Crane and Marta Kauffman would not have obliged: [from wikipedia] "Crane said that it took them a while to accept the idea of a tenth season, which they decided to do because they had enough stories left to tell to justify the season. Kauffman and Crane would not have signed on for an eleventh season, even if all the cast members had wanted to continue."

My question(s) are these:

1) If they had decided NOT to do a 10th season, how would you (or how do you think the writers would..) have ended the show? Erica (the surrogate) was not written in yet, Mike (Paul Rudd) was still a new character, Charlie (Aisha Tyler) was introduced towards the end of the 9th season, and Ross and Rachel weren't fully together. (My thoughts: they don't write in Aisha Tyler, Phoebe and Mike break up because they hadn't been dating long enough for marriage, and Chandler and Monica can actually have children without the need for a surrogate).

2) What do you think the episodes would have been about if there were a Season 11? Write about the twins or Phoebe and Mike trying to have their own children? Would they have run out of ideas? How would Season 11 (the final episode) end if Rachel is back in New York?