Interesting to note then that Tennant and Tate are being brought into a forthcoming special, I think they said, c/o Russell T Davies.
No real details if they'll be there as an N Doctors[1], so far as I can see, it could be as little as a flashback storyline, but it seems easy to imagine a Ten and Donna temporary timestream-crossover event or even a Ten+DoctorDonna[2] reprise.
I can imagine love and hate for any combination of these individuals[3]. While the promised Tegan/Ace appearance in the Thirteen/Fourteen transition episode is probably more a matter of huge love[4] from some or else 'meh' from others.
Confusingly, it seems like there also may be a 'Rose' character in the forthcoming series. But not that Rose. (I wonder if Ten might allude to avoiding the One Steve Limit? Obviously it's happened before, but it might be more pointed and deliberate given those involved.)
What is a shame is that such a high proportion of new-era (especially recent new-era) episodes are Specials that have to try to prove things. It's virtually expected that there's a Christmas Episode every year (or New Year one, if not) and one can't begrudge a "decades of" marker special, but the 'regular' weekly series runs (a la classic-bit-of-Classic-era; and early Rebot-era, including much of Tennant's tenure as Ten) has been somewhat sparse from the lack of either writing, willfulness or budget to make a decent spread of semi-linked serials that may or may not culminate in a grand finale that brings various planted threads together. Instead it's been pushed towards singular standalone 'spectaculars' in one, two or perhaps three parts (like I said I think the latest Sea-Devil episode was originally written as) and not much more.
[1] From memory, we've had at least two 2-Doctor mashups (not counting regenerations/Valeyards/visual flashbacks, one "dummy" incarnation (Jackson Lake), any involvement of the Fugitive Doctor and odd preincarnations like Capaldi's Lucius Caecilius[1.2] and C.Baker (Six) being Commander Maxil in a Five story), two different 3-Doctor ones (old era, new era), the classic Five Doctors (albeit one was left trapped in Shada footage/vortex thingy because of availability) and and the mini-parody Five(ish) Doctors (a core of three, an apologetic one, etc, in cameo form). Plus the new era 3-Doctor might be even considered a 13-Doctor (or 14-Doctor, if the Curator is indeed The Doctor but not actually classic-Four).
[1.2] Explained similarly to Romana Two choosing to look like a past storyline-acquaintence for (sub)conscious reasons. Though in Classic-series canon it was only Timeladies who could 'try on' regenerations and choose (male Timelords were subject to more chance and had stick with them), which seems at odds with Reboot-canon, especially as there is clearly no distinction between them anyway!
[2] Handwavily not vulnerable to the dangerous memories again/temporarily. I bet Davies can get the right story to spin whatever yarn is necessary to get past such a canonistic issue.
[3] Muted/outvoted with Tennant, perhaps, if you don't hate him for not being Eccleston, or are too young to have known his era, you probably appreciated his tenure. I was not a fan of early Tate myself but she grew on me a little; clearly somewhat overwhelming a character, however, doubtless making her a bit Marmite-like. Davis might be considered either as the reboot-showrunner that made the series what it is/became (for good or ill) or remembered more for his other projects (for good or ill!) so I imagine some will cheer and others will boo.
[4] Remembering the thoughts about how it was generally thought a shame that the Sarah Jane Adventures didn't quite get to present Ace's grown-up self, before the unfortunate Actor Existence Failure that forces an end to the series.