It's the same as it was before. We want to implement Trezor support, but we need to finish the new wallets first (our current wallet format is not compatible with Trezor).
What will be the changes on the new wallets that will allow it to implement Trezor that the current wallet doesn't have?
BIP32. All the wallet functions of BIP32 wallets are available to Armory users now, as it's wallet format already uses H/D address generation, but it currently uses Armory's own format (which won't operate with a Trezor directly). So it's just about inter-operating with standards defined outside Armory, basically.