Is the UK the "Austria" of European unification (in 1871 analogy)?

Is the UK potentially the "Austria" of European unification (in 1871 analogy)?

By European unification I mean not the current state of the EU but the potential political union, that would count of a unification analogous (to be compared AND contrasted) with the Germany unification of 1871 and the 20-30 years after that.

One of the policy issues coming out of such analysis is whether the UK can potentially be the "Austria", ie left out of the unification.

Another issue is whether European unification of the depth of the 1871 German one, will lead to stringer or weaker large members of the EU, namely Germany and France. And of course for the United Europe as a whole, and all its components 25 or more or less of the current member of the EU27.