NO NO NO NO NO! The ABA should not come back. And with good reason.
Say IF he were to to retire this year, have him win, 20-0. Come up with a way for him to retire honorably. The lights go out as he's doing his kneeling thing in the ring and on the screen it says R.I.P....? and then you here Undertakers laugh with a bolt of lightning striking his symbol and setting it on fire on the stage (its WM so maybe the druids could bring it out or something). Lights come back on and Taker is gone.
Vinnie, I think that your guess is going to prove to be 100% correct...when the actual time does come, be it this or next year, it will be more-or-less as you have described it. That's how i see it too, here is why...
Mark Calloway, as a wrestler, had been around as an active professional for years until he debuted at The Survivors Series, all those years ago. But what a start to his WWF life, his costume, his technique, his moves, his long unblinking stares, the long frock-coat, the re-work of the funeral march as his theme, the gong...
It is true that sometimes, the value of the final product can surpass the the values of its individual parts and it's visible here. In other words, there is a bizarre 'entertainment chemical reaction' where on-screen magic happens, and you realise that something unique has been created that is a fixed point in time, and it has never more obvious than with Mark's classic UNDERTAKER persona. People love it! It is as simple as that.
And as gimmicks go, it is one that will be regarded as one of the all time greats along with HULKAMANIA, The Excellence Of Execution, The Heart Break Kid, Macho Madness, WHAT A RUSH!!!!!, That's The Bottom Line, If Ya' Smell-lllllllllllll... and some others.
It is Mark's signature gimmick, it made him a HUGE national and international star, it is loved by fans all ages, it was a good idea but it realised just brilliantly and it is fair that he leaves the world of the WWE the way he entered it, as the WM-undefeated Phenom.
I am certain that Mark is aware of all the things mentioned here, he is not a stupid fellow, and I think he would see the sense in bowing out as he came in.
And, let's be honest here...when I hear that gong, and the choral introduction to his funeral march theme, I mark out like an 11 year old boy!