After ICO you can buy remaining SOMA tokens on their platform. Also interesting: "Soma will provide a "liquidity reserve" of SCT, which will only be utilized in a theoretical situation, for instance, if after the ICO the SCT is not liquid enough to support the functioning of the Soma platform." From whitepaper.
They wont burn it? Dont like that idea, i hope it doesnt backfire back on them. I dont see the reason of doing that since their ICO is going quite good.