I hate cookie-cutter polls - I'd rather pick MY answer instead of choosing from a very short list.
I think that the correct answer is "as many as GM makes" - and only GM can answer that question. I think that there will be enough demand to sell more than 50K cars, and that if GM builds 60K units, they will all get sold. The Bolt, with at least twice the range for just a little bit more $$$, will scavenge sales from every BEV on the market today, and most especially the LEAF. GM *might* go with caution, selling a smaller number to be able to fix (re-tool, or re-design) any problems, and then increase production.
The answer might depend on "as many as GM can get battery packs for", as that is THE gating item - it is a single-source part and if there is a supply problem , there is no way around it.
Lastly, I wonder if after several car companies (GM, Nissan, BMW, Audi, Kia, ...) have shipped a 200+ miles range electric, that Tesla will announce "We were just kidding about the model 3 - we just wanted all the OTHER car manufacturers to get in the game. We are sticking to luxury automobiles."