Rubio's number isn't as awful as some of us had suspected it could be, but if Kasich is actually closing on double digits that is terrible news for him. It points to the same kind of non-Trump pile-up that we saw in New Hampshire, with no clear winner for the portion of the party that isn't interested in Trump or Cruz. It also suggests that much of that portion of the party remains unconvinced that Rubio is a credible candidate.
You are right about a pile-up.
South Carolina is Winner Take All statewide, and by congressional district. Trump's lead over Cruz is similar in all 3 regions: Upcountry 38:18, Midlands 35:22, and Low Country 37:18.
Trump also leads a combined: Bush-Rubio-Kasich, Upcountry 38:34, Midlands 35:31, Low Country 37:36.
Trump is likely to take all delegates.