Though, that said, the need for InterCity bi-modes will reduce over time, while there are branch lines that are never likely to be wired - it's DMU or closure.
The thread on pollution levels at Birmingham New Street are a prime reason we need to kill diesels of any type when there's wires available. I'm hopeful of seeing greater deployment of bi-modes as we move into the 2020's, in particular on regional routes that will have part wires in the future, but suspect that will only happen once we get to the stage when the old 80's DMU's are really no longer fit for purpose and someone like the DfT make a firm long term commitment as was done with IEP to give manufacturers the confidence to invest in getting a local train type solution working in the UK - as things stand, TOC's haven't really got any other option but to use pure DMU or EMU solutions.