I am not a fan of stupid regulation but I simply don't believe that it would be impossible to find suitable replacements for wolfram bulbs, relegating the current equipment to scrap or requiring expensive refits. Right now nobody makes them simply because there is no demand. Once there will be, I am sure halogen bulbs or dimmable LEDs outfitted with the right sockets will appear in no time, given the size of the market.
I'm not familiar with the details of the regulation, but regarding the cost of retrofits: The workhorse of theatrical lighting is the ellipsoidal reflector spot, aka "Leko". The standard in the industry for that class of fixture is the ETC Source Four. Without a lens tube (since those are common to the tungsten and LED versions), the tungsten fixture body costs about $330 new, and takes a 575W or 750W lamp. The LED retrofit kit for the tungsten body (Source 4WRD) costs $599 and is meant to be photometrically equivalent to a 575W tungsten fixture. There is no retrofit equivalent to the 750W lamp version. So that's $600 plus labor to retrofit each fixture, of which a theater may have anywhere from dozens to hundreds, and applications that have been relying on the increased output of the 750W lamp may have to increase their inventory of fixtures by ~30%, which means buying complete fixtures with lens tubes--at least $1000/ea for Source 4WRDs, depending on the type of lens needed--plus additional cabling.
The other option is to buy Source Four LEDs, which cost about $2000 each. For flood fixtures, there's really no retrofit path, so that means buying new fixtures at $200-600 per LED par.
There are cheaper options, to be sure, but it's going to be exceedingly difficult to match the performance and reliability of these sorts of fixtures at a lower cost.
Native-LED fixtures require a data runs to each fixture, which means a lot of new cable to buy, and possibly new infrastructure wiring and distribution equipment. Older lighting desks may not be able to address the number of parameters required, especially since multi-color fixtures will require 3+ parameters each, in which case a new desk is in order, at a cost of anywhere between $10,000 and $80,0000, or more if redundant control or network processing is required. Venues that were designed for tungsten lighting (most of them) will probably need to have many of their dimmers converted to non-dim to be able to reliably power LED fixtures, so that's another $200 or so per circuit, plus labor.
Of course, most theaters and production houses are moving in the direction of LED already,
when they can afford it, which may mean buying a handful of new fixtures in a year. Being forced to upgrade everything in the next two years (if that is in fact what the new regs require) is going to be TREMENDOUSLY expensive to the point of impossibility for many organizations.