No, it shouldn't, as that's not what the term "market capitalisation" means. Market capitalisation only ever includes shares that are actually held by shareholders, not treasury shares or unissued shares. It's an important distinction because every single satoshi that has ever been mined can be linked to the address of whoever currently holds it, just as every share of a company is owned by a particular shareholder, and you can point to that person and say "this person has this many bitcoins and they're worth this much". And you can add up all these people to get the total wealth that people are actually holding in bitcoins. That's what market capitalisation means.
Unmined bitcoins do not form part of the wealth held by any individual, and therefore are completely worthless. As far as the economy is concerned, it's as if they don't even exist. The fact that they will exist sometime in the future doesn't change the fact that they don't exist now, and therefore shouldn't be counted.