That Xenos Inquisitor is meant to be out with one PA book
I think that what Inquisitor Eisenhorn is suggesting is that Inquisitor Lord Draxus may be given Kill Team rules in addition to whatever rules she gets for WH40K, much like Inquisitor Eisenhorn was given Kill Team rules when his model was released with WH40K rules.
I could see a new edition of Kill Team being released a bit later down the road, implementing changes/additions that we've seen so far as well as incorporating concepts from the WH40K rules (Astartes chainswords!). Since Kill Team is a separate game system, though, the publication of the new 9th edition WH40K rules doesn't directly impact Kill Team - GW has to update the Kill Team rules separately. How much GW changes the rules is open to speculation, though I don't predict major changes.
Some hobbyists would like to see Kill Team become a bit more like Necromunda in its rules, and I'm in that camp, but I'm betting GW will keep Kill Team roughly where it is - a modification of the standard WH40K rules. This is unlike the upcoming Combat Patrol which, if it remains true to its 40K in 40 Minutes roots, will be a small scale WH40K rules set. The differences being that Combat Patrol will largely follow standard WH40K rules with some restrictions in terms of army composition and points size, with units remaining the basic maneuver element for playing and army composition. Meanwhile, Kill Team remains a system based on individual models. The overall similarities between standard WH40K and Kill Team make the latter a great gateway into WH40K, with the transition being fairly simple. Practically speaking, Kill Team is a great gateway in either direction. Players that like the simplicity of the rules can step up to larger forces in WH40K. Alternately, players that like the smaller forces can step up to more complex rules via Necromunda. Entitled gamer that I am, I would love to see some sort of "Advanced Kill Team" that gives us the complexities of the Necromunda system while preserving the factions of Kill Team. That's not likely to happen, though.
Stepping back to my previous post, I could really see a new edition with updated and consolidated rules. Looking back at Rogue Trader, those rules were nothing more than watered down versions of what were later released as the Commanders and Arena expansions. What I'd really like to see is GW introducing new factions via expansions that don't include general rules, but which give us new factions. To illustrate, if GW consolidated all of the general system rules from the Core Rulebook, Commanders, Elites, and Arena into a new rulebook, and perhaps expanded it with a bunch of other stuff; and then they gave us a factions book that covered down on all of the existing factions (updated to include new units we're going to see soon in 9th Edition WH40K), they could then release "starter boxes" that feature other factions. Those boxes might include both generic rules for their faction as well as a specific example of that faction. For example, the Rogue Trader expansion might be turned into a New Dawn Crisis expansion. It would feature generic rules for using Rogue Traders in WH40K, and would also include the Elucidian Starstriders as its example Rogue Trader crew for the campaign. Similarly, we might have a generic Gellerpox Infected faction with the New Dawn Corrupted as the example Gellerpox Infected force for the campaign. This isn't that much different from how we have generic rules for a Genestealer Cult force in the current Core Rulebook and we had a separate boxed set for Starn's Disciples as an example of a specific Genestealer Cult kill team. In fact, GW might give us both campaign expansions that feature two (or more?) kill teams as well as individual kill teams. In most cases, I could see them initially selling the campaign boxes and then later separating them into two individual boxes for long term sales. Each of these options provides a stepping off point for expanding factions into standard WH40K (where appropriate).