When I inquired to AT&T about Tango for my Focus S, they sent me a reply about it and the Focus Flash. They had not included a roadmap for Tango for the Focus 2 (or the Titan, for what it is worth). The best thing to do is to send an email directly to them about your device. Just sign in under your wireless account and click on the "contact us" option. An email is better- if you call you will never get anyone who knows anything about updates. Emails are routed to the right department.
Still no Tango update for Focus 2! Samsung should be pissed about the poor support by ATT for their Windows phones. Nokia gets preferential treatment. Something to think about down the line for a Windows phone buyer.
I do not update my device even though Zune keeps b**ching about it. I heard nothing but problems from the updates for Samsung. I will update the phone when 7.8 comes out and even then it would probably need extra updates.
Still no update for Focus 2.
The official response for 7.8 is "The upgrade to 7.8 will be available for versions 7.0 and 7.5 shortly after the marketing of the devices Windows Phone 8."
How's that for ambiguity!