Microsoft has a Market Cap of 1.4~ Trillion.

They are 280x larger than that 5~ billion dollar number.

To put that in perspective, Microsoft's market cap is greater than Australia, Mexico, Netherlands, Saudi Arabia or Turkey's GDP.

Just food for thought.

Actually MS market cap is lower than than Australia's GDP but it's only around a 100 billion behind, and Market cap isn't the best indicator of a companies capacity to spend money it can go up and down a lot faster than gdp. after all MS went from 800 billion down to 250 billion before rebounding to today's numbers but it's purchasing capacity remained steady, still your point still stands, I don't think anyone in their right mind would argue against MS's capacity to pay that amount or even more.the catch is the xbox division is worth a fraction of that market cap and any expenditure would have to be seen from that perspective,so it really comes down to a business case and that's why we don't see companies making purchases just because they can.

My read of this is if it turns out true, is it would consist of a marketing/ branding deal covering Japan with SEGA making all their games be available on the SEGA branded console first along with gamepass day one availability,it may even see some games become exclusive in Japan.

They could also buy both Sony and Nintendo and no blink an eye and have a real monopoly in the video game market, there's a reason they don't and it's the same reason why this rumor is nonsense.  

Well, let’s compare this to what we know about Sega’s June 4th announce from the Japanese tech journalist:

-It’s a hardware announce, but it’s not called Dreamcast 2. (This lines up with Sega partnering with MS to sell the Series X in Japan. Even if Sega doesn’t call it the Sega Series X, they wouldn’t call it Dreamcast 2 in Japan as the Dreamcast was not all that successful on Japan. Saturn is their most successful console in Japan, so Saturn 2 would be a more likely name if they don’t plan to use Series X)

-It’ll rile up the gaming industry (I think it’s safe to say that a Sega-Microsoft partnership would shake up the industry quite a lot, depending upon just how extensive that partnership goes, if it involves Sega exclusives on Xbox it would really shake things up)

-It’s a scoop equivalent to Wired being allowed to officially announce the PS5 and some of its tech details back in April 2019. (I think that it’s safe to say that an exclusive story about a Sega-Microsoft partnership would be a pretty big scoop for a tech journalist. Would get a lot of clicks.)

Also worth noting that Sega site/channel SEGABits previously reported on a Sega-Microsoft partnership rumor a few months ago. In a recent video about the June 4th announcement, they said they still believe that the hardware announce may be Microsoft related.