Not going to happen.
I "suspected" that much.
Both compilation speed,
That's not a good argument, while it does require the compiler to keep track of more information, that information is usable in other areas in the compilation process. The net effect is usually negligible or well worth the advantages obtained. There is a little extra overhead upfront but, the information it produces saves time in subsequent compilation phases. The increase in the final usability is _substantial_.
and having to long term maintain internal compiler structures that way.
That is true of the internal structures it is currently using. There is no difference there.
FPC is set up as a production compiler, not as a research project.
We probably have a very different viewpoint on the subject but, to me, a production compiler provides as much information as it can to the programmer using it. It doesn't just generate code. Generating code is the bottom of the basement, IMO, a production compiler goes a bit beyond that. When I want the "minimum" and I want it fast, I go to McDonalds, they produce "food" (code) and they definitely do it fast but, in the long run, it's a bit short of something consistently desirable.
not as a research project.
Is that a way of saying that a compiler that uses something a bit more modern than 1960's compiler construction techniques is a "research project" ?... I don't believe Delphi is a research project and, one of the obvious improvements they have implemented is making the compiler a DLL. That way the RAD environment doesn't have to create a new process for every compilation (by the way, that takes time) nor does it have to communicate with the compiler using pipes (which is definitely far from optimal.)
This is the way why fcl-passrc exists.
And along with it, the overhead and hassle of having to keep it in synch with the actual compiler. "Research" has already shown, long ago I might add, that keeping multiple copies of the same thing in synch is nothing but, a never ending bag of headaches. It is things like the existence and overhead of fcl-passrc that is a "clue" that there is room for improvement there.
Again, just of the record, I don't have any illusions of FPC going that direction anytime soon but, it would be good if those involved in its development took notice of how compiler architecture is changing to better serve the user/programmer.