In terms of MTB, I sometimes ride with local level DH riders; the gap between me and them is fairly wide TBH. When I watch them compete against national level riders (e.g. at the BDS series) the difference is roughly the same, and then from watching world cup coverage there's a similar gap again between them and the world cup guys. It seems if you're at the top 10% of one level you're only at the bottom 10% of the next one up - a big difference between them basically.
Having only started road biking 8 months ago the same comparisons can be made to me, the leap up to decent club riders, then up to national level riders, then again at the top of that the international guys. You could argue there's another leap up to be able to ride the grand tours.
An example of this is the 'Horseshoe Pass Challenge', which is only a few miles away from me. I can do it in 24.32. Geraint Thomas did in 14.22. WTF? Maybe I could knock 30 secs off (on a really good day), but 10 minutes? And that pace over 150km?
Anyway, even after 8 months I'm still a mincer going downhill so I'd definitely crash within a few miles. So no, there's no chance