After this arc, it could be the end of SMG4.
(I also made an announcement on my Message Board about this!)
This whole arc has lasted a bit over a year now, and it's given us so many new things: the 2nd redesigns, the Showgrounds, SMG4's Castle, III's Coffee and Bombs, and even having Clench and SMG3 join and be a part of the SMG4 Gang.
On top of that, there's been a lot of character development and focus for each of the characters, and we've been able to see some of them grow as well as how some of them are vulnerable.
Over the last year and a bit, it's also been pretty obvious that Luke and the team have been trying to entertain their new and old fans, and 'It's Gotta Be Perfect' went into how stressful that can be to do sometimes. We've even been given 'Remastured64' episodes of SMG4's old content and even his first video only a few weeks ago! Maybe so that we can all be there when the channel comes to a close?
And the poster from Puzzlevision says, "Dropping every Saturday forever". Maybe it's a point of the fact that the opposite is actually true: SMG4 can't last forever, and that after this, it's the end.
And Luke was in yesterday's episode. What a way to go out, finally putting the creator into lore and having them be affected by the events that are happening in the fictional world as well. And combining the SMG4 universe and our universe and proving that they aren't that different and that they can both be affected by the media industry, the audience, us.
Glitch Productions has also only continued to blow up ever since 'The Amazing Digital Circus' was first released, which caused the channel's sub-count to double and even surpass SMG4's. (And MatPat did a few 'Film Theory' videos and shorts on it and 'Murder Drones' before he (obviously) retired.) So what if Luke decided that the company was more worth his time and effort instead, so he stopped SMG4 as a whole so that he could focus full-time on that instead?
However, I feel like if SMG4 were to come to a close, Luke would warn us or say something beforehand, rather than just abruptly ending it. The channel has run for more than 12 years now, and I really don't feel like Luke's the kind of person to just stop making videos without telling us that he was going to do so or without an actual reason why.