Adding the Bitcoin symbol to the keyboard will scream "ADOPTION". The question is where to put the key? I would suggest they replace the $ with the bitcoin symbol... just kidding. However, it gotta go somewhere, what do you think?
Outside of some sort of specialist keyboard then it's probably going to be decades, if Bitcoin survives that time and possibly becomes an official currency in other places, before such a thing would happen. Outside of maybe El Salvador there simply is no need for it to be on a keyboard and the design is already rather optimized to make best use of limited space. One other major challenge and the first step to such a thing would require getting the Bitcoin symbol added to every single major font so it would be readily accessible whenever needed, I don't think it is integrated into many font sets at all - also, why just Bitcoin? There are many other upcoming coins that may deserve it too.