An interesting move. Mixer has seen a lot of investment and marketing promotion from Microsoft, so merging into Facebook Gaming is an interesting choice.
Currently, the big players in the space are Twitch owned by Amazon, Facebook Gaming owned by FACEBOOK, and YouTube Live owned by Google/Alphabet.
More competitors to drive some innovation and reduce the market share of the leaders is healthy so it’s a shame to see a big competitor closing down and selling their user base. The article mentioned partnering but that isn’t the impression I get at all.
A very tough and expensive area to be in. Remember that Playstation has deals with Twitch integrations and the Xbox was naturally aligned with Mixer - which is likely to change to Facebook Gaming now. Making it even harder for new competitors in the market to arise.