Hello
There is no official timeline from Cisco, at least not in the public domain. Its more of a 'customers can expect' type of tone from Cisco . The bottom line is, you won't see any 'new' third-party support in MARS in the future. Apparently the 'existing' third-party devices will be supported, but I won't be surprised to see that change in the near future.
You can see the confirmation from a Cisco employee at the following link:
https://supportforums.cisco.com/message/939058#939058
These links are also useful (but without timelines):
http://www.gartner.com/DisplayDocument?id=1217745
http://news.idg.no/cw/art.cfm?id=CB2020C4-1A64-67EA-E46D690513A46239
Regards
Farrukh Haroon