I dont think there's much chance your bringing in Oladipo at 30 million ON TOP of Kemba, Tatum, Brown and Smart. There's about 115 million in those guys + Thompson tied up next year, thats five guys. Add Oladipo at 30 million and that plus 9 spots at the league min puts you at 160 million+ or about 30 million over the luxury tax. I could see Boston going 20 over MAYBE, not 30. I guess if you can get him so cheap year that you don't have to resign him then maybe, but I dont see that happening.
Oladipo is owed 21 million this year, you have to move like 7 million to stay out of the tax if you trade for him this year which I think they probably want to do since it resets the repeater tax and could save 10's of millions long term.
I think its more likely they go for somebody in the 8-15 million dollar range this year and stay below the tax. Then they either resign that person, or if that person walks they use the remainder of the TPE to add another 10-20 million in the offseason. I dont think you're gonna see a full 28.5 million added to the payroll next year.
But i could be wrong about the teams financial limits.