As much as I like Richard I don't like this news. His absence made me believe the MK/EC collaboration was a possibility 
Richard's presence on the recording doesn't mean Mark won't play with Eric.
There are plenty boring parts to play you know (strummed acoutics and all that stuff) that neither Mark or Eric bother to play
on albums like JJ cale tribute or road to escondido, there are plenty other guitarists to do boring rhythm parts, so there could be the same here.
You know, when Richard wasn't there (KTGC or tracker) there were far less Mark typic rhythm fingerstyle than on the records with Richard.
For examples, rhyhtm parts like this is us, cleaning my gun, silvertown blues, boom like that, you don't know you're born, postcards, remembrance day etc...all these songs have Richard on a third or 4th guitar while Mark plays THAT typical rhythm thing. and on the contrario, on albums where he is alone on guitars, there isn't any rhythm part like this
never understood that
