the most close to solving this is the experimental code made by
@xeroc and
@svk for a hackaton where they integrate trezor with steem, this code can be found at
https://github.com/chainsquadit should be possible with some effort to make this work for bitshares, this topic is always bumped from time to time. if i remember correctly the development stopped mainly because bitshares was waiting for an upgrade from trezor on their api that will make this thing a lot easier than it is now. Now it needs to be done in C, the new api will allow to do everything from python. new api was never released from trezor, not sure how is that at this days.
kencode also was starting a project for ledger-nano, a device similar to trezor as far as i know. initial code can be found at
https://github.com/Agorise/ledger-nano-s-bitshares but i think it was stopped for lack of funding.
if the bitshares community really targets this as a priority we will have a better view on what is needed than what we have now. probably need to hire someone with proven skills in trezor that had integrated other cryptos to it and work together with some of the bitshares devs to get what he needs, not sure, need to be planned first to have an idea of how much in $, time and in human resources this will need.