I doubt this "boycott" will have much effect as the people claiming they'll "boycott" likely had no plans to visit anyway.

But it's been speculated the travel ban will have visitors from other countries, not just the banned ones, staying away because the US seems unfriendly these days. I've saved comments from other thread, like these from the Guardian: "Tourists need to stop coming to USA. They come to America to spend their money on their holiday just to be treated like criminals. There are many other countries they can visit where they will be respected and have a good experience." “I'm not travelling to the US anymore. It's not safe with all these repressive policies being unveiled and an unpredictable, totalitarian leader who believes "torture works." Rumour has it that Homeland Security is now reviewing social media of travellers and asking about their political views. The US is now on my "no fly" zone."