I swear to fucking god Total War 40k is going to be the death of this franchise and the final nail in the coffin for CA.
There is ABSOLUTELY no way they can deliver on that promise considering their current state and recent track record, a game of this calibre would require substantial changes to the formula and engine that they simply cannot afford right now. Sure it might become an insanely profitable installment but the risk is just too high when they could just turn to other historical/fantasy settings that fit the current formula better and will probably be just as profitable maybe even more than 40k. I'm talking about Medieval 3, Empire 2, Lord of the Rings, Dune, etc... Dune is actually a perfect example of a potential game that would help them bridge the gap between a more traditional style of warfare and a modern one.
There's a reason why Warhammer Fantasy worked so well, if you look at other modding game conversions it was one of the most popular ones since most of what it needed was already there and it fit so well. Until they upgrade their framework and engine Total War 40k is going to be nothing more than a pipedream.