Unless a policy that's been in place for years & years is suddenly changed (and perhaps with the new organizational structure a new policy will in fact emerge), you will never get any sort of timeline or roadmap. 6.5 has been at RC1 for at least a year now and I'm not sure with 7.0 looking so good that there will ever be a 6.5 final. 7.0 beta 8 is excellent but anyone who knows if 7.0 RC1 is next, or will be preceded by betas 9 through 42 ... isn't talking.
I am personally holding off on replacing my heavily-customized home SME server until 7.0 final, whenever that might be, unless something horrible happens to that server first (*knock wood, rub lucky rabbit's foot, sacrifice goat, etc.*). I have put 7.0b8 into production in email servers on two different LANs and it is doing a superb job protecting two Exchange servers from the big bad Internet.