There is no fix for the issue. There is unlikely to ever be a fix for the issue as it's a hardware problem.
Regarding DOCSIS 3.1, yes, a new hub is required. 3.1 isn't going to use frequencies outside of the 3.0 range, at least initially, however it's a completely different technology from 3.0.
EuroDOCSIS 3.0 uses a series of 8 MHz wide QAM modulated carriers on the downstream and essentially load balances them. 3.1 follows the example of xDSL technologies and uses a series of much smaller OFDM carriers in a larger block. The 3.0 carriers are restrained as a single carrier can only carry as much data as the worst part of its spectrum while the 3.1 OFDM carriers can not only use higher order modulations more readily but also have more advanced error correction allowing for more coding gain.
3.0 permits a maximum of 8 bits per symbol, 256QAM, 3.1 goes up to 12 bits per symbol, 4096QAM, and indeed can get close to it in conditions where 3.0 only just manages 256QAM.
It also carries the added bonus that 3.1 modems lock to up to 32 3.0 channels, so there's up to 1.6Gb/s of 3.0 bandwidth available and shared with legacy devices, along with a gigabit or more (96 MHz wide OFDM block seems to be the cool thing, can be between 24 MHz and 192 MHz and can have more than one, these blocks seem to average around the 2048QAM mark) of 3.1 capacity.