GW is really the elephant in the room. Having said that, the last few times I've checked, their profits were steady, but their market-share was declining. The trick is to carve out a niche where they aren't, or do something to attract players that are disaffected with them. The latter seems the easier proposition to me, particularly for LoS/PS.
For people upset over cost, you'd be hard-pressed to be more expensive than GW. For those annoyed by the number of miniatures required, you have a small-scale skirmish game (that WH40k used to be). For those annoyed with poor rules and seeming lack of playtesting, you've got a tight ruleset that mimics real-world firefights well enough for those who've experienced combat to feel at home. For anyone upset waiting years for their favourite army list, you can release multiple armies together, then provide updates to all forces with new releases.
As for anyone who's a serious fan of WH40k, I doubt there's anything you're going to do to convert them, except over the much longer term. And I'd say that mostly comes down to them getting fed up with one or more of the problems I mentioned above.