For one, the part probably has to be redesigned, because all the characteristics are different.
For another, no one's making the high voltage BJTs like the old way. A 10 or 20V part would be easy enough to do. But that's nowhere near the original spec.
TLV2372 is probably an example of this, using a high voltage CMOS process (18V max). Though I don't know offhand if that's metal or poly gate HVCMOS -- there's poly HVCMOS, right?
Which is not to say there aren't any fabs doing that sort of thing. Discrete BJTs aren't going away any time soon. I'm not sure why they couldn't simply run a different mask set there (and insert a couple more passes for doping as applicable, and metallization; of course, doping can't be done willy-nilly, that's a whole process refinement step). Perhaps access to the fabs is poor (who's making BJTs anymore? It's not all China now is it..?).
There are plenty of HV processes, ranging from ~20V amps like the above example, to 50-60V regulators and switchers, to 600V+ gate drivers. Probably these are optimized for CMOS though, and BJTs are rough on a CMOS process. (Also, not that the 600V transistors in HVICs are necessarily any good -- they do actually exist, and the HVIC process isn't just a high side isolation thing, transistors are included and that's indeed how they couple signals to the high side -- but not much performance is needed for that, either.)
I suppose LT (now ADI)'s internal fab is one of the most likely candidates; they've been making interesting BJT-based parts for ever. There aren't many ways you can make a buck regulator operate from 2-30V, but BJTs are a good one. Datasheets don't usually say much of anything about internal design or process, so it's not obvious from here how much they do that, but obviously it's what they're doing when they show an NPN switch on the block diagram.
Going back to direct substitutes, there are plenty of >30V op-amps out there, some with quite impressive specs. I don't know how many are bipolar, BiCMOS or what. The biggest downsides will be: cost, knock-on changes (because the GBW, etc. are different), and approval.
Tim