I really like this trade for the Knicks although I honestly don't think that Portland would go for it. However, they're in a weird place right now as they just gave Lillard an extension and given his age, their window for contending is shorter than you might think.
I do think that Randle would be an asset for the Blazers though, while he had a down season, he's never played off of a truly great point guard and Lillard definitely qualifies. I think his efficiency would go up and he has averaged over 20ppg and 10rpg for quite a while now and is still a solid passer. He'd definitely need to give more effort on the defensive end to make it worth it for the Blazers. The Blazers also get the 2023 FRP from Dallas which may end up being fairly decent as the Mavericks will likely have a rough year. For the Knicks, aside from opening up time for Obi, Josh Hart is a solid veteran who puts up good numbers, is on a good contract and as a bonus, would continue the Villanova reunion currently happening at the Knicks (Brunson and Arcidiacono). Who says the Knicks just go for Kentucky players? Speaking of Kentucky players, the Knicks get to try and develop Shaedon Sharpe, the 2022 6th overall pick who has a lot of upside. I think his inclusion is what makes this trade so unlikely as even though the Blazers are in a weird win-now but not quite good enough quandary, they still spent the 6th pick on a developmental project with lots of potential upside. Anyways, this will likely never happen but wanted to give my thoughts!