I would think the larger political implications close to non-existent. Princip was a lone operator, and I doubt anyone would be rushing to his prison cell for opinions or advice about the new Yugoslavia.
As for what Princip himself would think, I don't know. What was the general opinion among Serbian nationalists about the formation of Yugoslavia? Possibly his would be much the same, or maybe not, but in any case, I don't think anyone would really care.