This issues seems to be fixed for me now. I added another google account and switched to it (only in Google App) for a while that was at least showing me the cards. Now I tried switching back to the the original account in Google App and it is working as expected. I still have the second account added though.
Btw, when the problem was there, adding only one account (not my original google account which had issues) also fixed the problem for me.
Now everything seems to be working fine. I an pretty sure this was at Google's end (server side) since no app update was pushed to fix this issue.
Update : On my Nexus 7 tab which was still showing the "New version available" message, I just tried refreshing by swiping down on the screen and I see the Google now cards.This device has only one account (my original account which had issues)
I hope this issue is fixed for everybody.