Well there are ~1,500 TZs owned by Pinsiders and ~1,050 TAFs, the top 2 on the "owned" list.

There was a post earlier this year asking what % of machines still exist, but no one seemed to have much in the way of educated guesses:
https://pinside.com/pinball/forum/topic/any-guesses-on-what-percentage-of-machines-still-exist/page/2

I looked at the pinside "owned" data and found some data for various production years:
1977-1980 = ~1%-3% reported as owned by Pinsiders vs. total produced
1981-1989 = ~2%-6% (Centaur and EATPM were the highest %s)
1990-1992 = ~2%-9% (CFTBL was highest at ~9%, TAF was about average at 5%)
1993-1995 = ~4%-12% (except for AFM which was a whopping 18%!)
1996-1999 = ~4%-19% (CC, MM, CV and MB were all on the high end)

I would guess that there are 2X-4X these totals still in existence - just a guess though. That would mean that about 2,000-4,000 (10-20%) of the 20,300 TAFs are still around today. But probably 1/3 to 1/2 oustide North America - I recall reading somewhere that close to half of machines were shipped overseas. Not sure how many were reimported though.

Yes there probably are a bunch more sitting in warehouses - although most in poor shape. What the heck are they waiting for - now would be the ideal time to bring them out! I doubt they are going up much more in value.