With Pre 90 and Pre 95 coming into the mix, the variety of available race bikes will diminish even more.
I'd actually say that pre-85 is the low point, in that regard.
The few pre-85 Maicos & KTMs aren't all that great, while there's simply very examples of the very few models of pre-85 (and non-Evo) Huskies around (and they're really nothing to get excited over, as serious race bikes).
In the second half of the 80s, the KTMs and Huskies got more competitive against the Jap bikes.
As you enter the 1990s, more brands start coming on line (Husaberg, GasGas, TM & ATK were all imported pre-1995, albeit in limited numbers), and the two bigger Euros started getting more serious about MX.
Into the second half of the 1990s, it gets better again with three of the four previously mentioned brands becoming relatively mainstream, and stuff like VOR/Vertamati, Maico and Cannondale also existing (albeit on the very fringes).
We're certainly spoiled for choice of new bikes ATM - add BMW, Beta, Aprillia, Sherco and the emergence of some reasonable Chinese brands. Will make pre-2010 racing interesting in 2025!
NB: This is not intended to be a part of the debate, just some observations.