My concern is not over UK not being kept, it is the news that drives peoples decisions and sometimes it is trying to create a sense of direction for the UK namespace.
If Nominet is hedging its bets and has plans to introduce a new tld if Scotland leave, then why would anybody register and spend time developing a .uk?
If Nominet has no plans then coming out and say so, it can only strengthen the new .uk.
I believe if Scotland left UK, it will still be know as UK and the internet space anomaly (as technically I believe, it should have been .gb, so we have always lived with an anomaly)
of the UK excluding Scotland would continue to use .uk.
If there is news that says that something else may replace UK, it creates uncertainty.
I would hope that Nominet would come out and state the UK brand will stay as is, even if Scotland leaves. So removing that tld uncertainty.