Canada is talking about sending troops to help currently. Would they shelter US deserters again while doing that or have dynamics indeed changed? I was around during and recall Vietnam era too.
They don't need to go to Canada to avoid a draft. They just need to keep on doing what they have been doing.
The "dynamics" have changed, compared to 50 years ago.
(Maybe that's the reason that Biden is inviting so many military age illegals into the country.)