|Interesting somebody brings up this topic since I was just thinking yesterday "where would they even find experienced and, more importantly, current Tristar pilots these days?"
Seems that the type has become a dinosaur. The only commercially available simulator is with Delta Airlines and the operators, as of last year, were:
Rollins Air (the Honduran company; the (in)famous "411A" of PPRuNe was involved in this thing first-hand)
Privilege Jet (leases from the Rollins Air)
I guess they do have their attraction for some fly-by-night, cash-strung operators. You can probably get an L-1011 these days for the price of a Cessna Caravan.
Having said that, Lockheed was rumoured to have planned web-based regulator and operator conference in July.
The subject is supposedly "wing fatigue management" but the subtext is really grounding the legacy Lockheed aircraft including L188 and L1011 by imposing an economically unsupportable wing inspection regime.