I think a lot of people will be thinking the same. Problem is that will also include the lucrative US / Chinese tourists who flock to London / Oxford / Bath etc. in summer - the areas where U.K. tourism makes most of its money.
In the bigger picture, the UK economy can cope with a year or two with little tourism - I’m not sure the same can be said about Greece, and that’s going to factor into decision making as to when countries choose to open their borders.
The other thing is different countries have different attitudes to risk - the Russians will start travelling immediately the direct threat is over, while the Americans will take several years to return to Europe in large numbers regardless of what happens next.