Not really.
Samsung is a huge conglomerate. Sure, it's profits went downhill in 2014 but it still made more profit than Toyota and all Japanese electronics companies combined. Don't believe me?
For fiscal 2014 (Samsung's worst year since 2011), Samsung still made $21.45 billion USD in net profits. That's more than these companies combined: Toyota ($17.76 billion USD), Sony (-$1.4 billion USD), Panasonic ($1.1 billion USD), Sharp (-$1.65 billion USD) Canon ($1.5 billion USD), Hitachi ($1 billion USD) and Toshiba (-$0.251 billion USD) combined ($18.059 billion USD in profits combined for the biggest Japanese automaker, Toyota + all the Japanese electronics "giants").
I think it's Apple which is most in danger of going downhill if smartphones and tablets ever become less popular. Of course, we don't see this happening in the foreseeable future. But Apple is much less diversified than Samsung.
And if Samsung ever halts supply of its technologically advanced parts to Apple, then Apple's in big trouble as everyone else like TSMC and Qualcomm are way way behind in FinFET technology. And Micron, Toshiba, etc are way behind in DRAM technology.