3 stars is the highest rating Michelin gives, anywhere. That's just how their scale works.
I wouldn't worry about how they'll rate Chicago until they've done LA and probably San Francisco. And except maybe for Arun's, I would expect them to completely miss the fact that Chicago has an ethnic cuisine scene at all.
I think the Michelin guides are way overrated and have a tendency to reward bad things about restaurants. I preferred the Gault-Millau guides, back when those were still published in English.