Like Spain and Russia, the UK is a multinational empire whose 70 year+ long breakup starting in 1947 is still an incomplete work in progress. The EU membership-Brexit issue kept the issue from occupying first place in the political queue. All three triggers of imperial breakup are present:

1. Rising economic volatility.

2. Divided elites

3. Failed or disillusioning military adventure (Iraq) undermining state legitimacy.

The key components missing in the UK case: Linguistic differences forming the basis of national identity differences.

The potential secessionist areas being wealthier and tired of subsidizing a central state they have no fiscal control over (Lombardia, Piemonte, Veneto, Liguria, Friuli, Emilia Romagna vs Italy, for example).