Really? People have been talking about it since the Bush administration. Until now things hadn't gotten bad enough for people to actually do it in large numbers, but people saying that if the Republicans win they'd move to Canada has been repeated so often over the decades that it became a bit of a joke.
Without the crucial steps the W Bush admin took, there would be no Trump. It's not that Trump isn't worse but they are part of the same fascist movement, just further developed.