Some more thoughts on this...
On the Marvel side (which is i think a reasonable comparison/standard), they have built a momentum that will keep it going for probably the next decade. Even if for some reason every single thing Marvel does from now until 2024 fails, there is still some juice to to keep going another 3 years, minimum. But realisitically, even if Phase 5 with Fantastic 4 and a revised X-Mne, completely fails worse than any other attempt the past 20 years, they
Marvel kinda over did it with the connections, in my opinion, with the Infinifty Stones in practically every movie... but it worked, not just for Endgame, but just bringing the universe together. SO we can get Dora Milajae in Falcon and WInter Soldier with zero problems, and it all makes sense. Again, they built the momentum so they could A) take risks with crazy stuff like Guardians of the Galaxy and WandaVision ... and they worked (as a whole), and set it up such that while some may want to stick with a particular creation (such as Black Panther), MANY people are excited to follow the next thing.... and have enough willing to even follow it through perhaps a rough start (my wife and oldest dropped WandaVision after the 1st episode, but me and my youngest held on, and felt rewarded).
And in both DC and Marvel comics, the heroes we have been seeing onscreen have been on the same planet (not just Earth, but that specific one), so it isn't unreasonable for many of us to want to have that...and it works for MCU.
It COULD work for DC, but DC feels to me like Sony was with Amazing SPiderman -- it seemed obvious that what they put out was more for getting money through the film rather than the joy of the IP itself. (i know it needs both, but the joy helps propel the success).
In regards to the Arrowverse, if they actually pace themselves, and market better, they might be able to keep it going.
I really with the movie side had worked WITH the TV side.... way back when Flash premiered, it really COULD have been integrated into a movie Justice League, and keep the big 3 on screen, and use the TV for the "2nd & 3rd tier", and the momentum could have fed each other.
One thing the Arrowverse seems to have that the DCFU does not is that even offscreen, it seems like the actors really like each other, and like to have fun with each other as well as with their Universe. They DCFU cast seems to kinda just be there for business, and then go their separate ways after the panel. The Arrowverse characters seem to have more fun (such as seen with the infamous Barry peace out meme at Oliver QUeen's grave), despite some hiccups (Andrew Kreisberg a couple years back, but now on a different vibe, with the way Brandon Routh and Domic Purcell have/are leaving)
The lack of planning, pacing and coordination over all of the live action stuff really is dividing a small fanbase, and not really growing a new one (the way Marvel has done).
They need to go back to what made Flash the number one show on the network when it first arrived --- it CLEARLY respected past work, in different genres. That made fans give it an exciting buzz, which created momentum to make it successful. It was its own thing that fans of previous work would totally respect and promote. That LOVE of the DC Universe is what's needed to make it work.
