I have read most of the posts in this thread and it looks like the conversation became very ...detailed. Which is good I supposed when we are talking about specific ways of implementing specific solution (multi-core support) into the game's code.
BUT...

What do you think about making completely new game, written in a modern way (code-wise) for modern machines (2019-ish)... but with exactly the same gameplay mechanics as the original? I mean: is it relatively possible to "abandon" OTT-Deluxe project (since - as I understand, hopefully correctly - it's code has apparently some architectural limitations which bottle-neck it's advanced playability on modern machines), and simply start coding ...let's call it Modern-TT with all the same principles of gameplay, all the same "vibe" as TT or OTT-Deluxe?
If I understand correctly, OTT-Deluxe is something like "restoration" of original TT. And my thoughts went around changing that perspective from restoration to remake rather. In other words - OTT-Deluxe project seems for me like taking Alfred Hitchcock's 1960 classic "Psycho" and restoring, upgrading a bit the original film material, removing some scratches, or flickering, maybe colorizing the shots, etc. And maybe Modern-TT should rather be like the Gus Van Sant's "Psycho" from 1998 (here you have comparison of those two movies to understand me better I hope: https://www.youtube.com/watch?v=xI_4LT7BTm4)
Don't get me wrong - I APPRECIATE EVERY HOLY LINE OF CODE WRITTEN BY OTT DELUXE DEVELOPERS!!! I'm grateful as gamer could be!! I Just love this game, and the fact that YOU GUYS made the effort of keeping it still alive is just one of those moments in life, when you believe in humanity

Regards from Poland!