The 3 is better than the S in size terms but it is still a large car in European terms. Width and length puts it equal to a Jaguar XE and wider than an Audi A4. Only offering a saloon with no hatchback also significantly limits the appeal.
I'm still not sure that even the MY will really come it at a size that really addresses the European market in the way that other car manufacturers are doing...
With batteries the way they are now, a larger car is pretty much necessary for a long range pack. The Bolt is pretty much topped out in the battery capacity department. While most people around the world want something in the 300 mile/450 Km ballpark, mid-200 miles is a pretty much a necessity for road trips in the US unless you don't travel much or are OK spending half the day charging. The distances in Europe are much smaller. London to Glasgow is around 660 Km, from here to San Francisco is over 1000 Km and that's considered a fairly short road trip.
There is a fairly large range of ~300Km EVs that are fairly compact and popular in the European market. Many of them are not available in the US yet and some may never be. Ultimately I think Tesla's competition will be stiffer in Europe than in the US. European car makers are more serious about making EVs (in part because the European governments are pushing the market that way, but also because Tesla has hurt European makers more than American thus far), the distances are generally shorter and the roads are tighter so people like smaller cars to long range and larger sizes are less popular, and Tesla is the foreign brand with a long wait time.
When Tesla builds a factory in Europe, that will help with the wait times, but it's going to be a long time before Tesla has a mass market car smaller than the Model 3/Y and they may never do one if the smaller EV market gets saturated with other maker's cars.
For the US market Tesla is going to have to make a truck and some kind of SUV built on a truck chassis. Full size pickups are the dominant vehicles in the US market. Personally I think it's ridiculous, but with all the trucks on the road, others want SUVs so they are up higher and can see around the trucks. A fairly large segment of the population also likes to entertain the idea they are going to go offroading in their SUV, even though most don't. Though AWD cars are also popular in places that get snow, especially places that get a serious snow only a few times a decades because those places have few snowplows. Economically it makes more sense to just not plow the roads and wait for the snow to melt. Around here Subarus are among the most popular vehicles. Going to the local healthy food supermarket the parking lot is pretty much 50% Priuses and 50% Subarus with some Leafs.
When we go into Portland and it's narrow, old streets near the center of the city, the cars get much smaller. There the ratio of Priuses to pickups goes way up. Most people in those neighborhoods would love to have an electric, but don't have a way to charge them. If they have a garage, it was built for a Model T and is used as a storage locker. Most people park on the street.
Anyway, I think Tesla will do OK in Europe, but over the long haul the European companies are going to have the bulk of the market share, though in the medium term the European market will be much larger as you adopt EVs more aggressively than the US.
