Sorry, but that's revisionist history.
The 1st and 2nd round pick were the items that had value. I'm not debating that one bit.
The 4th round picks probably had less value than 4th round picks today. Those picks became Reto Berra and Cade Fairchild, which is what you got in general with 4th round picks.
The older players didn't have any value back then. Trust me, I was a Canes fan and for a couple of them I said "Who?" Boulerice, Zigamanus, Nordgren and Kolanos were completely known entities and weren't going to be full time NHL players. They were throw-ins at best. Acting like they were otherwise at the time is revisionist history, they weren't, trust me.
Regardless, it wasn't "a lot of futures" which is what you claimed. It was a couple of good futures (late 1st and 2nd round pick), some mid-late round picks and a bunch of AHL fodder.
I'm not debating what a trade for Miller would entail or not entail, just disagreeing with your assessment that it was a lot of futures.
Yes, they were true rentals.
As far as it not being able to be done anymore, Why can't it be done? Did something change in the CBA to prevent it? (serious question as I don't know).