Sabonis is 24 and an all star big. Fits their timeline, productive, I can't imagine them trading him. Even Turner who is also 24, can't see it. Brogdon is 28, UFA after two seasons, I could see them considering trading him but for a younger player(s), not older player(s).
Indiana has a nice core of 24-27 year old players. Last season they were without LeVert (age 26) and TJ Warren (age 27), two pretty good scoring wings, for most of the season. If they get those guys back with Brogdon at PG, Sabonis and Turner as bigs, they certainly don't need Kemba Walker. They traded Oladipo to get younger as another example.
If I was Indy, I would sit tight and see how it looks with Warren and Levert healthy. I can't see them having any interest in Kemba.