I am of the opinion that long term these 2 are just not a great fit together. First off, I think it's ridiculous to bring a guy capable of averaging 20+ ppg off the bench. But instant offense! But crunch time! It's who finishes!
You need to play your best players against the other team's best players. If you cannot reliably do that, then you don't have the right combination of players. It would be great if they could start 2 guards that could average 18 to 22 ppg, but even if they proved able to coexist at that level, it is just not a long term recipe for success in the NBA.
So, who goes? I know the immediate answer is YOU CAN'T TRADE KYRIE!! Young stud! All star MVP! Uncle Drew! Yes Kyrie is certainly all of that. He is flashy. He gets to the rim and shoots from distance. He makes fancy passes. He shoots FTs well. Not many fans would be upset if the Cavs kept him and traded Dion. But is the easy answer the right answer? I'm not sure. So let's look at the case for trading Kyrie.
The first and most obvious point is that Kyrie would bring more in return in a trade. What would they get for Dion? A mid to late 1st rounder? A 'solid' vet? A young upside guy and a 2nd rounder? Kyrie obviously commands one really good piece (like a Kevin Love) or multiple young players and draft picks.
Scoring - Dion has shown that he can be a 20 ppg guy in Kyrie's absence. And oh yeah he can hit a game winner too(Bye, Detroit fans!).
Durability - Yes Dion had the knee thing (on a sweet dunk tho, amirite?) but is obviously more solidly built than Kyrie. That does not guarantee long term health, but at this point which one would you bet will miss more games in their career?
Position - Kyrie looks more like a PG, but is he really? Yes he can pass but he is clearly a score-first guy and his assist totals and A/TO ratio are good but not elite.
Leadership - Plenty of attitude and killer instinct on the court. Not sure he is a locker room leader but is still young. Could he truly be the alpha dog on a contender though?
So being that it takes two to tango, who would be interested in Kyrie that has reasonable assets to return? I mentioned Love earlier but could Minnesota really run with Rubio and Kyrie? Doesn't seem likely. Boston (Rondo, Sully, picks - meh), NY (Melo - not gonna happen), Toronto (Lowry, Derozan/Jonas, picks - ehhh), NO (Gordon, Evans, etc - no thanks assuming Davis untouchable), Sacto (Cousins, McLemore, picks - ehhh).
But one that does intrigue me.. and before I post it, I know what you are gonna say. They main guy in return is too much like Dion! That's why we didn't draft him! Problem not solved! But I don't think so this guy doesn't need the ball like Kyrie and Dion. I think he will be a guy who can impact a game in a lot of ways with defense, rebounding, slashing, off-ball movement. So...
Irving and Zeller for Oladipo, Vucevic, right for Cavs to swap #1 picks this year, #1 in 2015.
Deng or You-know-who, Miles
Plus a top 5 pick this year (Wiggins, Parker, Embiid, Exum, Randle) and 2 #1 picks next year.
Or substitute Harris for Vucevic and re-sign Hawes.
This will not be popular but I don't really care. I like it.