What about where they first meet and Cowl seems disappointed Harry is not yet heavyweight class? Marcone should have had a much better idea of Harry's power, and a timetravelled older Marcone even moreso. A Justin or Simon who has only seen him from afar (or from a fire?) or not lately would be working on a projection.
I agree. Future Marcone is Cowl is a fun idea, but it doesn't make sense for the reason stated above. Plus, Marcone would know that no new god like beings came about during the time of Dead Beat, so why would he even try to perform the Darkhallow? Marcone would know that the coup in the Raith's deeps would be a failure; he was there after all, so why would future Marcone / Cowl even bother with the scheme in White Knight? It doesn't add up.
As for those who bought into the Cowl is future Harry idea. Barring Cowl having lost all his memories of his younger self, we would have to believe Future Harry / Cowl engaged in the different schemes was saw in Dead Beat, White Night and short story Fugitive, knowing his younger self and allies would beat him every time. Future Harry / Cowl would have to have one hell of a good reason to put himself through so much grief.
We know that at some time Harry will break the Law regarding time travel. It won't be in Mirror Mirror, because that's interdimensional travel, it's not quite the same thing as time travel. The law breaking will be Harry chasing Cowl into the future; or more likely in my mind, into the past; perhaps to the events in Proven Guilty, if only to fix Little Chicago.
