If the EU ban on US travelers is put into play, will the UK also follow suit or is it not known? My wife is seeking to travel from the US to the UK as we've not seen each other for nearly a year and she has a pending UK visa application although she's not yet submitted biometrics.
Travelers from the US to the UK are likely to be allowed in but quarantined, according to UK Travel: How Quarantine Will End For Some Europe Arrivals, Not US (mirror) published on 2020-06-25:
Travelers arriving from France, Italy, Spain, Germany and Greece are among those who will soon dodge UK quarantine. And vice versa.
But the United States, Portugal and Croatia are not set to make it onto the list of countries with whom Britain is setting up quarantine-free “air bridges”, according to British media reports.
Update 2020-07-03: info above confirmed by https://www.independent.co.uk/news/uk/home-news/uk-coronavirus-red-list-travel-us-ban-lockdown-quarantine-latest-a9599241.html and BBC news: