Sitting here at the end of a long week at work with a couple beers... my thoughts go to my models... I'm missing playing 40k, but I think I mostly miss putting my models down on the table.
Having learned a lot about warmachine lately, I am seeing what is possible to do when you have a team of seriously dedicated people working for 10+ years carefully honing the rules and balance of a miniatures game system. The WMH rules allow for much more different actions your models take and more sophisticated interactions, yet players DON'T EVEN BRING THE RULEBOOK to tournaments because stuff just "makes sense" and rules confusion is quite rare. Model-specific exceptions and one-off rulings just aren't to be necessary. The idea of a "community faq" like the Adepticon for Warmachine is actually absurd, even though the game is more complex.
And get this... WMH has absolutely no force org. At all. You have a bring 1 warcaster/warlock, and there are zero other restrictions (except that some character models are inherently unique or limit the # of copies you can bring of that one unit to 3 or so). Yet, if you look at a lot of the championship level armies, they are basically highlander armies. Why? Because Privateer has done a great job of making their units balanced and constructing the game in such a way that you tend to need a lot of different stuff to win.
Thus, over the last couple of months, I have come to believe that the only way to make a good game using the (superior) 40k models would just be to write an entirely new game from the ground up.
I would actually advocate an attempt to build Warmachine-compatible factions that use 40k model range. Imagine... imagine being able to actually play a 40k army versus a Warmachine army. THAT would help us wargamers figure out who was better really quick
And I wouldn't be leaving my multitude of unusual 40k armies to languish. If I were like a millionaire I'd be trying to do exactly that.
There's no reason it wouldn't work. Transports (WMH doesn't have em) would be easy to make rules for. Vehicle damage would actually be a lot more fun if used the WMH "crippled system" approach.
Of course you'd probably get sued by both Games Workshop and Privateer press.