i'd take anything like that with a pinch of salt - it comes when it comes.
WHMCS will never give any commitments as to what versions will contain which features - the only time they do, is when a release is very very imminent (or more likely just after release!)...
my assumption has been for months that the next release will be sometime in May - if it's v7.7.2, it will arrive out of the blue without any warning (e.g it could get released in the next five minutes or we could still be waiting in June)...
if it's v7.8, then it will be classed as a major release and should get a beta release first - and that beta period should last about a month.
as to what the release will contain, I have absolutely no idea (and as you can tell from what you've heard them say themselves, WHMCS don't know for sure either!).
if they say they're holding this back until v7.8, then it won't be included in v7.7.2... if the next release is v7.7.2, then I wouldn't expect to see v7.8 for a few months after that.
there are supposed to be 3 major releases this year - we've had the first (v7.7), so I assume v7.8 will be the next major release and then v8 towards the end of the year.