No, we are not in fact 5 years from breaking RSA-2048.
I have no idea what NIST means when they give 5 years for 2048 bit keys, but in generally I trust them more than some random poster on the internet.
My inclination would be that it has less to do with the keys getting broken in that timeframe and more to do with moving to larger key sizes as soon as possible. As pointed out by others, RSA depends on the asymmetric difficulty of multiplication vs factorization of integers, but the degree of that asymmetry has no hard bounds. Advances in mathematics could reduce it, and NSA may already know of or at least suspect the existence of techniques which are not public. Larger key sizes mitigate against these developments, and pushing the software and hardware stacks to their limits sooner rather than later allows both the vendors and standards bodies to adapt before cryptographic breaks actually occur.
Maybe check who you're responding to then ;).
He's not djb but definitely not a “random poster” either.