It all depends where Tesla is sourcing their raw materials, like aluminum and steel. If they already source in the US there would theoretically be no price increase associated to the vehicle, at least not in these early rounds of the trade war since tariffs are imposed on raw materials only.
If their supply chain for aluminum is from Canada (which I believe is the case) they get slapped with a 10% duty/tariff charge and that may or may not reflect on final price, depending on whether Canadian suppliers discount prices or grant some back-end benefits to mitigate the effects of the additional tariffs. Also Tesla may decide as a business decision to absorb the added costs in part or even completely. Allow me to doubt this will happen.
As for Model 3, since it is built mainly of steel, depending on its supply chain it could mean a 25% tariff on raw materials, or nothing at all, depending on its source.
If things sour up, there has been threats that car imports to the US (finished products) would also get hit by tariffs by up to 25% as well. For Canadians this would pretty well mean the end of car exports to the US and a world of hurt for the Ontario auto industry. Canadians will obviously retaliate and if what we've seen so far warrants the future, it will be done strategically in order to hurt regions that have elected Mr. President and may represent swing votes in the future. This would logically jeopardize a lot more Michigan auto industry than California.
Also, in a bid to improve Canada's environmental balance sheet, it is not impossible that trucks would be hit harder than less-polluting cars.
Does this mean Tesla would be exempt from the effects of a trade war between Canada and the US? Hardly. But I expect it would not initially be the hardest hit.
This is one side of the trade war only. There are other facets where impacts will be felt and that may hit Tesla hardest:
If the auto industry in Canada were to be hit by tariffs, this could potentially seriously jeopardize north of 8k well-paid jobs as well as deepen Canada's global trade deficit (already deepened to $2.8B in the month of May). This will weigh on BoC's decision to increase its preferential rates and ultimately devaluate the loonie by as much as 10-15% for as long as uncertainty about trade war will last.
This last effect will weight much more on Canadians' purchasing power than direct tariffs as it will have a broader economic impact. This will negate the capacity of many Canadians to purchase imported cars, but tourism will be affected. For an idea how this affects the US: every major city in Canada, except for Halifax and St-John's NL is connected north-south with the US, while there is one single 2-lane highway connecting Canada from east to west. This is highly indicative of the amount of money that travels southward and could be affected by a sharp devaluation. Think shopping, week-end escapades, vacationing south, east coast, west coast. As Canadians rely heavily on imports for fresh produce, food being for the most part an incompressible spending budget, the effect will be multiplied for non-essential spending, such as travelling and... gasp! car purchases, including high-end, like Tesla.
The impacts are much more far-reaching than what is expected at first glance and will affect everyone, including those who have nothing to do with the trade war, near or close. Since the North American economy is so integrated, a tariff war has side-effects that are both far-reaching and difficult to quantify so stay posted and take good notice of what unfolds.