It wouldn't really surprise me. Intel's 10nm was pushed back to mid 2017. Intel's 7 nm would have to be out around 2020, then 4 nm in 2023. That's with no delays and no intermediate node between 7 and 4 nm (5.5 nm?). I think GF and TSMC having 7 nm in 2018 is very optimistic. Most like those get pushed back. Also the naming conventions are not the same across different companies. So who knows if GF's 7 nm is really equivalent to Intel's?
The wild card is the last process shrinks have proven to be harder and harder to pull off each time. If 4 nm is really pushing the physical limits then there could be a lot of challenges to get there. So, who knows, it could come earlier, but based off recent history I don't think a decade is that far out of line.