The Portal hasn't necessarily fucked college BB. Hardly in fact.
I'm old enough to remember when freshman were first allowed to play varsity, dunks were outlawed then re-allowed, the shot clock came into being and then reduced from 45 to 35 seconds, the emergence of the basketball camps, and the 3-point line being established, then extended, etc.
Every one of these changes to college BB was heralded as the beginning of the end for the game. And every chicken-little was wrong. The game evolves. The successfull coaches and programs evolve with it.
You make a reasonable counterpoint, I think. We're pretty fragile, collectively, as a fan base right now I think. Easy to start letting your imagination running towards worst case scenarios at times like that.
One thing is, there will be a bunch of programs in Iowa's position (i.e., having to learn how to adapt to a situation where there are higher prestige, more successful programs pilfering your best players). Obviously, it would be great to not have to worry about that...but, that's the direction the wind is blowing, so either adjust your tack or learn to love life at the bottom of the standings.
Here's the other thing. Think about this from the player's perspective. There's no contracts. There's no (real) money to be made. Even at programs like Kentucky where you know they are paying at least their top tier guys, I tend to think it's not "independent wealth" type cash. It's more like "a little extra spending money and car for your mom" kind of money - enough to get you through a little more comfortably until you are draft-eligible, in other words.
To make a long story longer, these guys really don't owe these programs anything. They're essentially free agents. Sure, we all love it when we see a guy who really, truly seems to bleed Black and Gold like we all do. That's great, but it's not something that can be forced, relied upon, or tested/assessed with any degree of reliability. It's really an individual personality thing on the players' part as I see it.
When Coach Cal (or, more likely, Coach Cal's proxies) came knocking at CJs door, we all would have liked to believe he would have made his back rigid, thrust his chin in the air, straightened up his letter jacket and said "I, sir, am a Hawkeye. I bid you good day." But it's clearly not like that for CJ. The grass looks greener on the other side to him, he had an opportunity, and he took it. He's out nothing other than leaving a bunch of disappointed Hawk fans in his wake but, let's face it, none of us have any bearing whatsoever on how the rest of his life will play out. CJ's never going to have any meaningful contact with any of us.
It sucks, but CJ's not breaking any rules or causing any real harm. Again, he's a free agent. He's taking his talents elsewhere.