So just lots of speculation at the moment?
And does the H1 in 2017 H1 mean 1st half of the year?
So we could be waiting till June / July before launch?
When AMD and most other companies say something like H1, they mean May-June, they just don't want to say Q2 so uninformed people will mistakenly think Q1.
Nothing I have seen indicates otherwise. June will be 1 year on from Polaris which fis AMD's roughly yearly schedule. At CES last year AMD demoed Polaris and we got the final boards 6 months later. So Far AMD have provided less concrete information on Vega than they did about Polaris last year.
If AMD are using HBm2 then they probably have to wait until at least then to get supply.
So unless we hear otherwise I would stick to AMD's H1 (may-June) timeline and be pleasantly surprised if things come in April. The latter is not impossible but liekly the minimum time frame.