In all honesty I think Moffat's trolling us here, I mean how can you seriously say that you're 'looking forward' in an ANNIVERSARY EPISODE?
If he's trolling then in reality there's probably several other familiar faces will show up, it doesn't even have to be old Doctors, the older companions could suffice if worked properly (I'm talking really old, like Jo Grant, Romanna, Leela, Susan?)
If he's serious, well expect BBC to be flooded with Moffat boycott requests quite soon.
Honestly, I don't think Moffat's suited as showrunner, he tries to tell all these big epic overarching stories, most of them end up feeling rushed and are riddled with plotholes,
Say what you will about Davies, at least his overarching plots were simple and tended to pay off at the end, Moffats either screams in your face that *THIS WILL BE IMPORTANT LATER* and has bits and pieces of the finale's story explained and advanced in other episodes whereas most of the season finales in #10's time had a couple of hints scattered about with most of the arc done within the last couple episodes of the season.
& before anyone says I'm just a Tennant fanboy I'll just say that its not that #11 is a bad Doctor, he's just had bad scripts to work with.
P.S. the Parallel universe #10 has a TARDIS, so I would not be suprised if some sort of spin-off show comes along after this.