The potential and the concern exist today, the difference being that there are more materials used to protect the underlying wood products. For instance, there was a lot of discussion on whether a stairwell or an elevator shaft should be required to remain made out of concrete or whether those could safely be built out of wood products. They talk about double-layering gypsum board around it. The protection from fire is equal once you use double layers of gypsum board or whatever.
The difference right there is that with concrete you don't need that to protect it from combustibility. The difference is that if the gypsum board is breached, or modified, or vandalized, the wood could be exposed behind it or there might be a conduction of fire—something that conducts the heat into where the wood is and results in the wood behind it being on fire.
Again, from experience, I have been in a situation where we're ripping out a floor, looking for the fire, because we're seeing smoke and flames, only to find that the products that are actually burning are a significant distance away because of the conductivity of heat and how the fire occurred. Once you modify or remove the layer of protection from the wood, or breach it in some way, it no longer has the same safety protection.