I wouldn't be expecting any terminal moves at LHR that don't relate to T2 for the foreseeable future.
The long term plan is for T1 and T3 to be demolished as the new T2 expands.
All airlines in T1 have to move by Oct 22 this year. Some airlines in T3 (mainly Star Alliance members) are moving to T2.
There would be space for MH (and QR) to move to T3 later this year, but it would be pointless since T3 is due to be shut down around 2018/2019.