I searched my entire cloth runtime library and found one(1) clothing item above 20K.
So at least if we speak about clothing it appears that if you can't do anything useful under 20K + normal/displacement maps you are in the wrong business.

Things might be different with castles and the like so I did another search in the architecture folder.

This time I found 20 item between 20 and 50k, one item was 89K (I have much more architectural items).

So if your piece is already 68734 polys you are in for a tough sell.

It is not about what Poser and the computer can do its about what the users want.