Your company plan sounds very much like how Valve is structured. You may find it challenging to maintain your desired organizational structure, given that you also plan to be dependent on external investment. Also, starting a company with the express goal of selling it as quickly as possible conflicts with several ways you might operate your company to achieve a high degree of success. Many of the recent small studios that have gone on to generate large amounts of revenue (relative to their size) (Terraria / Minecraft / etc) are independently owned and build 'service based' software that seeks to keep the community engaged.
Alexei, I would suggest an alternative and encourage you to apply to Valve. 1) It wouldn't take much of your time to try. 2) It may help you reach your goals more quickly. 3) You don't have to invest in building a rational organization, (which is costly and hard) since one already exists.
It would be a career oriented decision (few people leave Valve once they start there) and I know you are interested in applying yourself to existential risk as completely as you can, but you should consider the path of getting really good at satisfying the needs of customers and then through that, directing resources towards the existential risk problem. It may feel like you are less engaged, because you aren't there solving the hard problems yourself -- and if you have a high degree of confidence that you are the one to solve those problems then maybe you should pursue a direct approach -- but it is a path you should give serious thought to.
I wouldn't advise you to go work at any random company. Most game companies -- particularly large ones -- are structured in a way that doesn't mean you'd have a good chance of individual success (versus working anywhere else or doing something else).
Valve has one of the highest profits per employees in the world and is wholly owned by the employees. The company compensates very well. So my advice is specific to considering an application to Valve.
Are you still intrested in making this company?