Well, I don't look at fictional unvierses as shows but as the universes themselves. In other words, I see a world just like ours except that these character and all that is associated with them live in it. That's easier to do with sitcoms obviously, but can be done here.
So, here's how I see it.
The pilot of anything need not be canon, though they gave a nice explanation of why Oscar went from orange to green. (And of course, he may have thought it'd be more grouchy too - you know, it's not easy being green.
) Looks, etc. of things can be explained (Danny not cleaning for a while was due to depression over his wife Pam's death on "FUll House") or ignored (the joke on the Cosby Show pilot, "Why do we have 4 kids?" "Because we didn't want 5" can be ignored, or we can bring the Count in to bump the numbers up one.)
Having the Count bump the numbers up one makes a nice segueway to...
The Magical Years. 1969-1983?
Everything was so amazing - people could just appear on Sesame Street at any time. There was a sense, when I was growing up, that it was a fabulous place where numbers and letters danced and talked, all the monsters and humans got along so well, and I really don't remember much in the way of concrete street stories. That coudl be not recalling it well becasue of my youth (I was born right about when it debuted), but from what I've read on here there was a time when there weren't the specific street stories.
I don't know when that era of specific stories began, but I place it in 1983 for a reason. Not knowing when ATC came in...
The World Expands - 1983-1998? (or whenever ATC ended)
The universe of these Muppets expanded to cover much more when Mr. Hooper died. It is unknown how the other Muppets dealt with his death (That would make a *very* interesting fanfic!), all I know is how big Bird learned of it. In the Magical years idea I have, however, it may have been their first experience with it.
This jives nicely with the ATC being an addition to SS. Now, I don't remember anything of Around the Corner since I wasn't watching then, but I presume it was a way to show there was more than just this magical place, that there were a bunch of shops and such past it? That's what I'm basing this on.
Suddenly, these Muppets and humans that also lived there found there were other things they could see. New characters appeared, Snuffy from somewhere, Rosita all the way from Mexico, and so on.
Now, the ending of ATC has meant a new era, which comes with the block format.
The Sesame Street Show - 1998-present
You probably don't recall my comment a number of years back that SS has gone from being just a magical place to seeming like a choreographed show a la The Muppet Show. Elmo eventually became the star, then others were added. It's got a feel like the characters are just putting on the show and maybe do stuff in their spare times. Some of the street scenes are part of the show, some of them are independent, backstage.
So, what of the shops around the corner? To quote one poster on here, DrTooth...
I'd honestly hate to think that Around the Corner has turned into a massive bunch of shuttered stores that no one has bought (or leased) the storefronts of. Or worse... a ha;f building that was supposed to be condos until the company went bankrupt. Man, I HATE that. There's this one area that was supposed to be a series of condos and an Ikea... for years it was a vacant, ugly lot. They're actually doing something about it now.
That would be terrible if that happened on Sesame St. Then again, if Starbucks and Urban Outfitters moved in, would Ernie and Bert still afford the rent at 123?
I don't think you have to worry about it being run down and abandoned. Remember, in my mind, there is a separate universe here, and this is where, among other things, the theater exists where they put on the show, where all the celebrities come when they are supposed to interact, where the kids painted that crazy set of murals with the numbers we all love to hate, and so on. And, instead of a boarding house of The Muppet Show, or wherever they lived, we have 123 Sesame and the rest of the places on Sesame Street.
"But wait," you might say. "If you're saying this has to be realistic in-universe, does one of the muppets own it all? but they're all young kids, right?"
That's true, but we can all have our own theories. Bert and ernie as college students rooming together is one I like (though I still like to think they're brothers or at least cousins), and so on. Maybe one of you thnks Elmo's parents bought it and that's why they insisted he be the star.
However, there really isn't anything in-universe to suggest any of them would own it, and besides, wouldn't a human have to own it?
Actually, there is one, if you'll allow me to cross over universes for a second. And it's an idea that fits perfectly.
See, there's a certain 6-year-old girl named Eloise who resided previously at the Plaza Hotel with her nanny, not far from Sesame Street, one whose mother is quite wealthy, it seems. I can easily see her deciding that her first foray into business would be buying up all the shops in the ATC area when things started to go bad with the economy, and transofrming it into a great playhouse where the Muppets can put on shows for the kids of the world. So, she builds this theater, has people helping her hire Muppets and such, and so on.
Yes, it's quite a silly idea, and I'm sure others have different ideas in-universe for why things work the way they do. But, that's the fun of imagining things in-universe, using your imagination.