Test format is still England's favourite out of three. The issue is England is losing interest in cricket at a whole.
I think the veer onto limited overs is ECB's plan to try and get the younger guys/ children into cricket.
Think ECB's to blame, they sold cricket to sky sports taking it off free to air. And in general disregarded LOIs for a long time until they realised it was becoming to much of a part of the future.
The interest in cricket in the youth generation is an all time low. It's actually the British Asian youth population which is most enthusiastic about cricket, and they don't even tend to support England.