Not overly concerned. In the free world, competition will step in if the price goes up, like what Samsung did with high-end MLCC caps.
Besides, I like Yageo resistors. Good quality, and never had problems with them.
Kemet certainly is not a rival to Yageo.
Kemet has no interest in cheap consumer market, and Kemet doesn't even make parts smaller than 0402.
Kemet makes high end, innovative parts for medical, industrial, automotive and aerospace customers.
OTOH, Kemet has kinda outdated equipment, not nearly competitive to Asian companies. But their management is good, and workmanship is good.
Besides, unlike Yageo being a component company, Kemet is really a material company.