Let's back to the Header on SMG4 Channel:

Four new details can i appreciate are:

1. Mario once again doesn't look glitchy

2. Shroomy's face change to his Demon Slayer form

3. Bob is turning to Rob a little bit

4. The 4 in the SMG4 Hat changes to the skull of SMG3's Hat

   Rapid Conclusion: Maybe in the next chapter, SMG3 delets SMG4 and the Header is going to appear the anti-cast (SMG3, Mario, Rob, Jub Jub, Belle, Whimpu, Weegee Doll & Melony)