How that might play out...I'd like to go the opposite direction and have our current Doctor meet a Doctor from a very distant, future regeneration. It might even be fun to frame it from the Future Doctor's perspective and somehow have the current Doctor not realize who he's working with.
DOCTOR ELEVEN
Wait! You were me all along!
FUTURE DOCTOR
Oh, I suppose so, old boy. (Beat) Or should I say 'young boy'?
DOCTOR ELEVEN
But which me are you? Twelfth? You're not the thirteenth and last, are you? Oh, dear...
FUTURE DOCTOR
(Raps DOCTOR ELEVEN with his cane)
Balderdash and poppycock! You didn't believe that old nonsense of Borusa's, now did you? Oh, of course I did.
(Pause)
I'll have you know you stopped keeping track after the five hundredth regeneration. When you reach fourteen thousands years old, it simply doesn't matter anymore. It's not like I can remember any of my very early yous that well.
DOCTOR ELEVEN
Five hundred regenerations...
(Pause)
A few hundred years ago I told Clyde that Time Lords could regenerate five hundred and seven times just to shut him up. I didn't think I was right.
FUTURE DOCTOR
We all make lucky guesses at times. Even me, when I'm young and don't know any better.
DOCTOR ELEVEN
Hold on. Have I been a woman? Or worse...?
(Pause)
A ginger?
Wait! You were me all along!
FUTURE DOCTOR
Oh, I suppose so, old boy. (Beat) Or should I say 'young boy'?
DOCTOR ELEVEN
But which me are you? Twelfth? You're not the thirteenth and last, are you? Oh, dear...
FUTURE DOCTOR
(Raps DOCTOR ELEVEN with his cane)
Balderdash and poppycock! You didn't believe that old nonsense of Borusa's, now did you? Oh, of course I did.
(Pause)
I'll have you know you stopped keeping track after the five hundredth regeneration. When you reach fourteen thousands years old, it simply doesn't matter anymore. It's not like I can remember any of my very early yous that well.
DOCTOR ELEVEN
Five hundred regenerations...
(Pause)
A few hundred years ago I told Clyde that Time Lords could regenerate five hundred and seven times just to shut him up. I didn't think I was right.
FUTURE DOCTOR
We all make lucky guesses at times. Even me, when I'm young and don't know any better.
DOCTOR ELEVEN
Hold on. Have I been a woman? Or worse...?
(Pause)
A ginger?