I'm completely new to 40k, probably will never buy the minis, but the lore is more and more intriguing to me. I'll probably get to know it slowly over the years so I'm glad there's a series coming. Yeah, I hope it's not watered down, I got drawn to this exactly because of the complexity, uniqueness and brutality of the 40k universe. I love Sci Fi in general, watch a lot of shows and movies that have at least some Sci Fi elements, but other than the Alien/Preadtor universe and the Doctor Who universe to some extent, I'm just not that deeply invested in the lore of other Sci Fi IPs, not to mention I don't even watch or like Star Wars and Star Trek. But 40k looks like something that's very different, a great blend of brutal Sci Fi and classical Fantasy. It's got u unique charm.
Keep it pure and true to the original and I'm sure people will like it. Not to mention, never underestimate the word of mouth of an old and dedicated fanbase, if they do right by them, it'll work.