Just indirect clues such as the radar tested.
And this team reportedly awarded the contract in 2019 to develop bridge control hardware that greatly improve automation for the new generation frigate.
A new generation frigate in the work is quite certain. The question is when will it appear. Many sources are saying sooner than later.
Other hints are:
Electric propulsion system. Since we're seeing EALS on 003, the electric propulsion system for 054B isn't far fetch.
100 mm main gun
General purpose VLS same as on 052D/055.
Z-20. 
