That is absolutely true, however the majority of European sway is with Germany, and the lost tourism would hit other countries (Greece, Spain, Croatia) much harder.
There will be a hit in tourism, but I doubt that it will happen on those three countries. When Americans go to Europe they tend to focus on France/Italy; Spain is more popular for Europeans. Think about tourists in Miami (searching for sun) compared to tourists in New York (searching for "history").
There's a ton of tourists in Germany during summer though.