Is mixing Clojure with Python a good idea?
In such scenarios I personally like to start in the below sequence.

Divide the system into subsystems with "very clear" definition of what each system does and that definition should follow the principle of "do one thing and keep it simple". At this stage don't think about language etc.
Choose the platform (not languages) on which these subsystems will run. Ex: JVM, Python VM, NodeJs, CLR(Mono), other VMs. Try to select few platforms or if possible just one as that does make life easier down the road in terms of complexity.
Choose the language to program those platforms. This is very subjective but for JVM you can go with Clojure or Jython (in case you like Dynamic languages as I do).

As far as Clojure future is concerned, this is a language developed by "community of amazing programmers" and not by some corporation. I hope that clears your doubt about the "long term" concern of Clojure. By the way Clojure is LISP, so you can modify the language the way you want it and fix things yourself even if someone don't do that for you.
I am working on a big project that involves a lot of web based and AI work. I am extremely comfortable with Python, though my only concern is with concurrent programming and scaling this project to make it work on clusters. Thus, Clojure for AI and support for Java function calls and bring about concurrent programming. 
Is this a good idea to do all the web-based api work with Python and let Clojure take care of most of the concurrent AI work? 
Edit:
Let me explain the interaction in detail. Python would be doing most of the dirty work (scraping, image processing, improving the database and all that.) Clojure, if possible, would either deal with the data base or get the data from Python. I except something CPython sort of linking with Python and Clojure. 
Edit2: 
Might be a foolish question to ask, but this being a rather long term project which will evolve quite a bit and go under several iterations, is Clojure a language here to stay? Is it portable enough?