The only console that could have any chance of releasing this year is if Nintendo announces a revision of the Switch. You can't just shadowdrop a totally new console out of the blue, it's suicide as Sega learned with the Saturn. The closest you see now are special editions or variations like the Xbox One SAD.
The only way Nintendo has any presence at the Xbox show is if we're getting a rep in Smash that would still make more sense the other way around other than the spectacle of having someone like Sakurai on stage, since it would be for a Switch exclusive game. Maybe the person that's in charge of "Nindies" if Ori on Switch is happening.
I don't see Sony having any presence on a Microsoft stage for a long time, if ever. The PlayStation team was not aware of the possible streaming game partnership until it was announced, that deal was made above their heads. As is, there is nothing for them to come out an promote, the only real cooperation we've seen is Sony finally relenting and allowing a few third party companies to do cross-save or cross-play, with the only direct link to Microsoft being the PS4 Edition of Minecraft, which has NOT been upgraded to Bedrock Edition presumably because of the Xbox Live requirement and cross-play. If anyone was going to show up it'd probably be Shuhei Yoshida, who I believe confirmed that he was not attending E3 or even coming to the States currently.