Regardless of the ideology of the court majority, they very rarely directly overturn previous decisions. It's not impossible (Brown vs. Board of Education) but it isn't just a matter of getting a challenge before a liberal court. The previous decision is binding, they would have to justify why they would be going against authority equal to their own.

I don't claim to understand SCOTUS - but they are extremely conservative institution. I mean dictionary definition of conservative - upholding the status quo. And they prefer to not get involved in the day to day affairs of the country.

So even a bad SCOTUS decision could stay on the books for a long time - just to save face and uphold the credibility of the institution.

They look to rock the boat the least. Even in their current hyperpartisan state.

With the Senate refusing to do its constitutional duty and confirm Obama's (very conservative) pick, it'll depend on who wins the presidential election. If it's Trump it'll probably be someone from left field completely unpredictable. With Hillary it'll probably be a middle of the road jurist not really willing to overturn things too much.