It's not really a promised or conscious boycott. It's after weighing the pros and cons, many of them intangible, the feeling is visiting the US right now could result in unpleasantness ... and if there is anything Canadians are adverse to it is unpleasantness. Anecdata: a friend of ours crossing the US border, despite being a VP at a bank, for her first time ever had to surrender her phone for examination by US border agents. Who needs that!
I assure you, there is also a conscious boycott from many people.
You are right that it might not necessarily be a hard boycott, but it will take a hell of a lot to lure them into giving Trump and his supplicants a cent of leisure travel.
Yeah, it's the same for me, I'm in Europe but I have places to sleep in the US. I was supposed to go this summer with my family but the uncertainty on how we'll get treated at the border (last time wasn't great for those of us who struggled with English already, I can't imagine what would have happened under this admin).
It's sad because WV might have like 15 European tourist every year and we're 5-9 of them depending on the year, but we'll take a year off, that's OK.