Is CPU upgradable in 2018 mini?

It is not using a desktop processor its using an intel B series chip which is a mobile chip like all past Mini's. I don't know of any Mac mini that has has the CPU upgradable post purchase and yes its soldered in place.

 

They said in the keynote it wasn’t a mobile processor.

Do we know which actual processor it is yet?

 

It is at least possible. I bought a first gen intel single core mini off ebay and installed a dual core MB processor into the same socket. But it may not be still possible.

 

no one knows for sure what they did.
I am guessing it is desktop and replaceable.
go to dell and look at its optiplex 7060 micro
i think the new mini is a riff of this.
in many ways better then the dell

 

It's soldered in. Very clearly shown in the image on the website.

 

Soldered in and NOT replaceable.
Get the one you think you'll be happy with when you "buy-in".

 

Get the one you think you'll be happy with FOUR YEARS FROM NOW (get it now, but plan four years down the line)