I think the R's will keep the Senate. Might be with a smaller majority, but looking at the state by state races there's only a couple that are really vulnerable plus maybe one or two others that are somewhat vulnerable. There's also a D or two that are at least somewhat vulnerable. Probably unrealistic to think the Rs will come out with the same or more Senators, but keeping 51 seats is quite probable.
Garland is probably the best we could hope for from Obama. If the R's retain the Senate I think we'd see a worse nominee by HRC if she won (shudder). But not Sotomayor bad. If Trump gets in Garland is probably still the best we can hope for. Otherwise we'd get a Souter/Roberts turncoat type. Cruz, with even a 50 R Senate (so he veep being a tiebreaker) would get us a much better Scalia replacement. But getting a Thomas/Alito clone through with anything less than a 60 R Senate will be very hard thanks to the filibuster. The media will try to let the D's get away with trying to run the clock for 4 years on Cruz.