If you could make up the plot for the last ever Doctor Who, what would it be?

Mine would be this:

Every bad guy Doctor who has ever fought against comes up against earth and all of his allies in one final showdown. Anyway, it looks like the dr is gonna win until the bad guys bring in some notorious bad guys (maybe the daleks?) and the dr trys to get his assistant away becaue he knows they have lost, but she is badly injured and dies in the tardis. He sits there, crying over her, and looks out over the earth which is destroyed completely. (you get the sense that he is literally the only one left in the entire universe.) Then he starts to to think about how throughout his life, anyone he loved has either died or become lost forever. So he (somehow) turns back time, to the pinnacle moment where he became the doctor that we know and love. (massive flashback through every dr who moment ever) and he's this child being taught about being a timelord, and he can (i'll leave it to you to decide your ending) either:

- have exactly the same things happen again, except this time, he does something that stops the massive war between bad and good guys, and dr who continues as normal

- he makes the decision not to be a timelord, and it just ends with darkness. (because there's no light without dr who!)

ANYWAY... what's yours?