Hello,
I dont think this post landed on the "Ask the Expert (Mynul)" section. Currently Cisco is still supporting both platforms but yes the goal is going to be to slowly replace pix with asa. Basically the ASA is a new/better version of the Pix with more options and features added in. If you are still running a pix its not like its a dead technology but if you are thinking of purchasing something new I would suggest an ASA if your budget allows it. (Please Rate if this helps at all)
Good luck,
Chris