I want SC and have ETH.... not the other way around. But to answer your question, you can hold it on their UI wallet yes... and soon on Jaxx too I think.
This is what I wanting to do.
I am willing to get siacoin with the eth I have or even bitcoin but needed to know where i can hold them so I can trade with you.
But I will wait until they are offered on a wallet as you said so they are easily transferable into whatever coin you want them into.
Thanks for the info.