OK, here is a first draft regeneration scene marking the debut of Matt Smith's Eleventh Doctor, shamelessly inspired on the Devious version, but with some new material:
(The ailing Tenth Doctor stumbles into the TARDIS and fiddles with the controls. A clock can be heard ticking.)
Eleventh Doctor: (vo) It's not going to work, you know.
Tenth Doctor: What?
(The Tenth Doctor turns and sees the Eleventh standing across from the console, arms folded, wearing his costume and everything.)
Eleventh Doctor: Guess who!
Tenth Doctor: What?!
(The Eleventh Doctor waves.)
Eleventh Doctor: Hello. I'm who you SHOULD be.
Tenth Doctor: But... that's impossible! You... you can't just...
Eleventh Doctor: I *can* just, and that's why I'm here.
(The Tenth Doctor looks his successor up and down.)
Tenth Doctor: You're a bit young, aren't you?
Eleventh Doctor: Age is what the looked-upon feels, not what the looker-upon sees.
Tenth Doctor: Good answer. I like it. (cheer fades) I take it, then... that time's up?
Eleventh Doctor: Time's up. (shrugs) Sorry.
Tenth Doctor: I'd just got used to the hair and everything, too.
Eleventh Doctor: Yeah, pity about that.
Tenth Doctor: So what happens next?
Eleventh Doctor: Oh, come on, Doctor. I mean, if YOU knew that, where would all the fun be in it for ME, eh?
Tenth Doctor: Do you have an answer for everything?
Eleventh Doctor: You tell me.
Tenth Doctor: Not helpful.
Eleventh Doctor: Tough. That's the way it's got to be.
Tenth Doctor: Jings. (frowns) Hang on, just a second, just a second! How do I know you're real?
Eleventh Doctor: How do you know ANYTHING is real? The Daleks? The Master? Donna, Wilf, Martha, Sarah, Jack, Rose and everything that's happened since you so nearly got to Barcelona?
Tenth Doctor: (to himself) Barcelona. Never did get there in the end.
Eleventh Doctor: Afraid not.
Tenth Doctor: I suppose a quick reprieve's out of the question, then? Just a couple more centuries?
(The Eleventh Doctor shakes his head with a helpless expression.)
Eleventh Doctor: Time to stop dwelling on the past and look to the future.
Tenth Doctor: You're not ALWAYS this bossy, I trust?
Eleventh Doctor: (grins) Only one way to find out.
(The Eleventh Doctor crosses to the console and, acting like he owns it, flips a control. A panel lights up. He places his hand on the panel. His hand glows.)
Tenth Doctor: (sighs) Well. No time like the present, eh, Doc-tah?
(The Tenth Doctor moves to the other side of the console, presses a similar button and places his hand on a panel as it lights up. The Eleventh Doctor reaches out with his free hand, as if inviting a high-five. The Tenth Doctor doesn't look eager. The Eleventh Doctor gives a hopeful grin. The Tenth Doctor sighs.)
Tenth Doctor: Oh well... ALLONZEE!
Eleventh Doctor: Snap!
(The Tenth Doctor gives the Eleventh a high five. As their hands meet, a glow surges up from the TARDIS console and around the pair, crackling and sparkling for a long moment. The Tenth Doctor grins. The pair grow brighter. The Tenth Doctor's expression becomes pained. The Eleventh dissolves into the glow which swirls around the Tenth Doctor, flares brightly and slowly disperses, leaving him swaying unsteadily next to the console.)
Tenth Doctor: ...jings...
(The Tenth Doctor sets the time machine in motion, then sways and falls into the pilot seat, looking totally knackered. His view of the console, time rotor pistoning, blurs and darkens. His eyes close. He is still.)
(We cut to his limp, fighting hand. It glows and gently morphs into a different hand. We cut to his head and his grows younger, hair longer, becoming the Eleventh Doctor in a smooth, unfussy manner. For a moment he sits there, asleep. Then his eyes flutter open and he looks around in mild confusion. He looks down at his body and ill-fitting clothes, and frowns in concentration.)
Eleventh Doctor: Ohkaaaaaaaaaaay.
(He unsteadily gets to his feet, swings over to the console and peers down at the controls, not having a clue what they are or how they work. He sinks his head in dispair as the TARDIS continues on its journey...)
(The TARDIS spins through space towards the site of Moffat's era.)
(The TARDIS lands.)
(Inside, the sudden halt snaps the Doctor and he rises from the console. Moving around the panel he peers at the monitor, showing the world outside. He stumbles down the ramp, his momentum carrying him to the doors. Dizzily, he flings them both open to reveal the landscape outside.)
(The Doctor stands in the doorway, looking around unsteadily. He addresses someone we cannot see as he staggers from the TARDIS.)
Eleventh Doctor: Morning! I'm the Doctor now, you know.
(With a queasy expression, he falls flat on his back... at the feet of a young woman with long red hair and a distinct Scottish accent. Played by Karen Gillan.)
……………… THE END