The limit should easily be beyond 150M, especially if people like Chris are right and they utilize saved money from the past few years. So I accept your premise, but the numbers should be higher.
While what you say here is correct, literally all of it falls into one of my two qualifiers so we agree.
My take is that one of the benefits of building this way is payroll flexibility. The ability to add talent to push them over the top. The ability to find extensions with talent they want to retain, and extend their window.
I have no definitive opinion of if they will take money they didn't allocate in '18-'21, and place that back into the roster. Color me skeptical. I don't care, I just want them to spend when they're ready to be good, which should be now.
I think it's perfectly reasonable to assume they were building a war chest for estate taxes.
I also have no problem with the Angelos family just saving some of the $ for themselves vs. spending when they didn't think it mattered.
I do think when the team is ready to contend (and that's now and going forward); they owe* it to the fanbase to utilize their limited obligations and add pieces to push them over in-terms of likely contention odds. Especially in scenarios where they don't have to give up player capital, and can just add via $. (Trades where they give up little player capital but take on contracts also apply.)
Ultimately, I think they should get back to their '16-'17 levels of payroll + inflation. ('17, $164M is $198M today.)
That isn't going to happen all at once, when multiple positions are going to be making very little for sometime.
But as you stated, and I agree... multiple ways to leverage this.
*However, if they came out tomorrow and said they don't ever want to spend... and they want to operate like the Rays... I'm fine with that. But be prepared to actually operate like the Rays.