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To not bury the lede, I don't think it's likely that velomobiles/full-fairing bikes/ebikes will ever become established as a notable fraction of the micro mobility segment.
As for why I think this, it mostly is down to what such bikes can do which cannot be done by other, more common bikes. Essentially, I think the market is really narrow for velomobiles, with no reason to expect it to grow substantially in future.
A velomobile is a full-faired bicycle, such that it has the lowest aerodynamic penalty of any human-powered transport, capable of achieving exceptional speed. While the focus might be on the fairing to provide protection from the elements, I think the aero profile is the strength and the sheltering merely an ancillary benefit.
Today's common bikes have their place, and ebikes expand upon that to cover more destinations in the same time, or the same places faster. Speed does open riding opportunities, depending on how comfortable you are mixing with higher-speed auto traffic on busier, faster roads. So it sounds like the velomobile should slot in perfectly to further expand the space where ebikes make sense today.
But we're reaching some limits with speed. A class 3 ebike can do 45 kph (28 mph), which in many places statewide and definitely in Europe, that's roughly the most common city/town speed limit. Going faster necessarily entails moving up to arterial roads or country roads. But there's nothing beyond that: bikes of all types are typically prohibited on a freeway/motorway. So the extra speed benefit of a velomobile is only realized for select road types which often have destinations far between or are generally uncomfortable for cycling outright. While some people will endeavor to make these journeys, it's not as common than cycling around town or to the grocery store. Thus there's a much narrower market for more speed beyond an ebike.
For sheltering, the adage of "there's no bad weather but bad gear" comes to mind. Cyclists from Hawaii to Sweden have found ways to adapt to their changing weather conditions, finding it more efficient to protect the rider than protecting the whole bike+rider. The velomobile must then compete against the affordability of mittens, a balaclava, rain-shedding pants, and water-proof boots. And all those clothing accessories are useful while off the bike. The economics don't favor the velomobile here either.
Will there be people who still choose the velomobile for other reasons? Absolutely! And I encourage it, since I want to see a live one on the roads. But I cannot envision a future where the velomobile grows beyond the realm of intrigue and novelty, because its micromobility competition is fierce.