Ron declares he is working on a new Monkey Island

[Gffp]

@Someone

Later Ron wrote that the ending of MI2 was created during and very late in the development process of MI2.

@Ema

Yeah, maybe he wrote that. But he also said this in 1990:

@LowLevel

This isn’t a historically accurate game. In fact, you’ll see when you play that there are a lot of anachronisms, like the vending machine at Stan’s used ship yard. They’re there to add humor to the game of course, but they also have a secret, deeper relevance to the story – but I’m keeping that secret for the sequel.
Source .

@Ema

If you read the content of the interview with Bill Tiller, it’s pretty clear how all flowed:
I was told that the ending of MI2 was originally going to be the ending of MI1. But Dave Grossman and Tim Shafer didn’t like it and talked Ron out of it. Then I heard from Larry Ahern that two to three months before MI2 was supposed to be done, an ending had still not been decided upon. And about then Ron decided to go with the amusement park ending he was originally going to use in MI1.

So basically the “It’s all a creation of a kid’s fantasy in an amusement park” was an option available for Ron since TSOMI. But was effectively resumed only a few months before completing MI2 and developed deeper in the way we all know now.