The FINAL Doctor?

So I was thinking about Doctor Who today...because I see there is a trailer for the new Christmas Special...which I didn't watch.  However this got me to thinking about the 50th Anniversary special.

Sorry if this is spoilers for a 3+ year old show but there will be spoilers.  So, if I remember right, at the end to save the Time Lords they call ALL of the Doctors.  All 12...NO 13!

So wouldn't this mean that this is the last doctor?  Because if there are more shouldn't there have been more Doctors showing up?

I realize that I'm probably thinking this through too much but should't there have been at least 24?  

Or are they saying that this only happened because the Doctor eventually got an extra set of life from the Time Lords TRAPPED in the whatever clever plot device they thought of that week.  

But if that is what was going to happen shouldn't it have already happened and affected the timeline? 

So then all the next 12 should have been there right?  

Yeah...I'm bored at work is that obvious?