Until the 'C' word is reached, there's no change.
I wonder if you call 75% of miners a consensus. Because it's not, it's ridiculous. There's a high probability it can possibly go wrong with this approach, I simply detest it.
It conforms to all the current limits and is following the current protocol to the letter. Ergo, it's Bitcoin but with a vote for a possible future change. It sends and receives Bitcoin transactions on the Bitcoin blockchain. It. Is. Bitcoin. If it had already forked and was producing 8mb blocks on a separate blockchain without a majority agreeing, then and only then would it be an altcoin.
It is extending the current protocol in its consensus-enforcing part. Because it says: after 2016-something if 75% miners have done something, we can produce larger blocks. It implicitly states it can do something the current protocol doesn't allow, under certain conditions that you call 'consensus' (which is far from the real consensus). It can disguise as an ordinary client in the meantime, doesn't matter, it won't make it Bitcoin.
It's not like protocol will be changed only if 75% miners agree, it's already changed by
adding this very condition. Protocol amounts to all consensus-critical rules, implicit and explicit, that are written in the software.
Imagine if I came up with a new IP protocol (for argument's sake we'll call it IPvXT Grin ) that added support for new features for the internet but only if the majority of the internet used it. Until then it remains fully compatible with the current IPv4 or IPv6 implementations and you argued that using it means you aren't using the internet anymore. You're using an altnet. It just sounds farcical.
The analogy is flawed, because internet is not a consensus-critical network. There can be any number of protocols in use, e.g. IPv4 and IPv6 currently. Internet is not defined by a single universal protocol, Bitcoin is.
If XT deviates from Bitcoin's blockchain without consensus then I'll be right there with you dismissing it as an altcoin, but until then you either sound like you're calling it an altcoin out of ignorance or malice. I honestly can't decide which it is.
Oh ok, so I'm either ignorant or malicious. The possibility of yourself being wrong is not even considered, I guess.
