They might need MS for applications where a high elasticity is desired. Mundane clothing such as socks, panty hose, sportswear, etc. would be good applications for it. DS would be better for applications where a higher strength and lower elasticity is desired such as jackets, vests, lining, and tents.
Now, once this new Über Silk is perfected and moved out of the lab into production, i think it will replace MS assuming it has actually started in Vietnam by then in the same way that DS has replaced Big Red.