Firstly it was not Serato it was A&H that said the controller was discontinued and will not get the necessary firmware upgrade to run Serato DJ. So blame A&H for not making a Serato DJ compatible firmware.
Yes there are people that are able to do that and run both, however mixing the 2 together you would need another external mixer and play both soundcards into that mixer. Also while some people can run it, I have a lot of feedback (no personal experience) that it is not quite stable on some PCs. So your mileage may vary and the whole setup might not work for live situations, where you want a 100% stable environment.