I think it's naive to think that business won't resume: money talks at the end of the day. Look at all the countries with awful regimes we have good relations with. The UK wasn't doing much trade with Russia before anyway, so I doubt it'll be doing that much after, but countries that were - and, yes, Germany is pretty high up that list - will slowly resume trading. Right now, a lot of companies are voluntarily limiting trade above actual sanctions, that'll roll back in a few years, and formal sanctions will get wound down over time too. I expect the stuff targetting the military will remain in place the longest.
