Irving opting in for a 3rd year would cost him $9 million, it's a non option. 2 years at $18.8 and $20 million for Kyrie is a steal and two seasons should be enough time to sell him on the future off whatever team acquires him.
The Suns are have been wanting to move Bledsoe, swapping him for Kyrie is a an upgrade. Swapping Dudley for Bledsoe (who have similar contracts) is better for the Cavs because Dudley can actually defend and shoot unlike Shumpert and would be something that the Suns may offer to do to sweeten the deal. Bledsoe is an downgrade but is a much better defender and has a connection with Lebron.
The Suns would essentially really only be giving up a lottery pick for Irving, considering that they already have Chriss, Bender, Jackson, and Booker already on roster, all of whom were taken in the lottery in the past three drafts, that shouldn't be that big of an issue plus they would have Miami's 2018 pick (probably ends up being 16-20)
Cavs pick up a very good PG but not quite the player that Irving is, they get Dudley who is better than Shumpert, and add a probable top 10 pick (while also having their own pick in 2018)
Suns get the best player in the deal and can pair him with Booker while still having Jackson, Chriss, Bender, and all there picks (minus the 2018 pick) plus Miami's in 2020. The Suns would be in good position to add a third star given all of their assets going forward.