The fact is that no one knows, not even Intel. Many hoped-for technologies have failed to pan out before. For example, the industry had placed high hopes on EUV lithography (in 2007 they hoped it would be ready by 2010), but continued problems make that technology look less and less likely today, at least for the short-term. III-V semiconductors are another major hope for the industry (a hope that's been around for decades), but now delays have pushed that from 10 nm to 7 nm. Imec has been working for over 10 years on a way of growing III-V semiconductors in tiny trenches to make it cheap enough, but until they actually ship product, no one knows if it's good enough to work.
It's a scary time for the industry, as Moore's law comes to an end.
(All that said, even if no one knows for sure what's coming next, that doesn't mean nothing will. The semiconductor industry is throwing billions of dollars and thousands of engineers at many potential solutions in parallel. Even if plan A falls through, there is always a heavily researched plan B, C, and D.)