Any kind of air strikes or something are extremely unlikely, I'd say, as getting involved in a military conflict near Russia is very high on the "things not to do" list. Not as high as getting into a war with Russia, but still.
What will happen is an investigation and if they can determine who was responsible there might be international warrants and if someone can get arrested, a trial. This will largely depend on the cooperation of the rebels though, who control the crash site and have the black box. It will also depend on Russian cooperation.
If (and that is a big IF) it could somehow be proven that Russian weapons were used in this or that Russia is in some way responsible, that might lead to stronger sanctions (there are already people calling for that), but not much more.
On the other hand I can imagine that Putin might consider dropping support for the rebels, if they bring him trouble like that.
It doesn't make any sense. If the rebels did it, they would risk angering NATO. If the Ukrainian government did it, they would lose the support of NATO. Both parties have the capabilities to do it, but neither would gain from it. I think that it was a case of mistaken identity-somebody thought that they saw a hostile aircraft, and instead shot down an airliner.
That is the way it looks like right now, the rebels mistook the plane for an Ukrainian plane. Even if it was just incompetence, that is still pretty bad.