I don't think you realize how much more MS is worth compared to EA.... Just to give you an order of magnitude... MSFT market cap is more 720 billions EA's is less than 40 billions .... MSFT does around 90 billions a year in revenue and 20 billions in earnings EA does less than 5 billions in revenue and less than 1.5 billions in earnings....

without going into details... EA is a dwarf compared to MS and pretty sure from past data that valve revenue is under EA's remember valve only gets a fraction of the steam price.... Anyway in the 2010' they were under a billion in revenue doubt that number quadrupled over the past 7 years...

people around tend to forget MS is among the biggest companies in the world when it comes to it's financials

To be honest, I don't see MS changing anything with Steam if they brought them. They will most likely keep Steam the way it is and probably merge there gaming libraries together which will benefit Steam owners since majority of Xbox games are not available on Steam. Much like how they brought Minecraft and didn't change a thing, if anything they added so many more cool features.

Buying Valve is more a PC move than a console move, it will also help there Xbox division a little with Valves IPs but the real boost is with the PC gaming space and having Steam as your default Gaming App on Windows will mean a lot more support and maybe more games built from Valves chest.

Anything can happen, Nintendo or Sony could buy Valve and they can make it amazing and they could also ruin it. This is something we can only assume right now. I personally love Steam as much as anybody however I am finding myself slowly moving away from it due to competition. Steam needs a little shake up, they are that far ahead of the competition however the drive is slowing down. I am tempted to buy games on Win Store now due to the Play anywhere feature.