So we now have 4 Tennants. 10th Doctor 10.5/11th Doctor Meta Crisis Doctor 14th Doctor How about a story involving all 4?? That would mean you could bring back Rose & Donna too.
You know how they love to bring back Tennant - maybe the next time the ratings are low, or the 70th anniversay?
No, I see it as you have: 10 - the doctor regen from Eccleston. 10.5 - the partly regenerated doctor that stayed looking like tenant (the doctor himself said this is a separate regeneration in Smiths final episode) The metacrisis doctor born from the doctors hand. The 14th doctor.
it used up a regeneration but its not separate. Can't be because that energy was needed to create MetaChrisis Doc
Eccleston is unobtainable while Davies/Bad Wolf are involved. So probably permanently, which sinks my fantasy miniseries spinoffs with Eight and Nine culminating in a crossover. So I'd settle for an Eight appearance or two. You forgot Jenny.
If a Four Tennants show were to be done or even considered, it'd be because the show is in the midst of another ratings emergency. Much as I love Paul McGann, he's not the solution to a ratings emergency, while Eccleston won't come back. Unless they got Joe Ahearne to direct, but that ain't happening either.