£31 is the point at which they'll make some kind of return on your service.
I doubt that. A marginal customer on the existing network would probably be profitable at around £18 a month including the costs of customer acquisition, billing, modem and connection to the premises. These increases have very little to do with the token speed increases, and are simply down to the Cable Cowboy milking the customer base. When he's squeezed the pips he'll sell it all on to some desperate but clueless corporate buyer.
OFCOM being clueless doesn't help, because VM's hand is greatly strengthened by the botch OFCOM have made of regulating Openreach. If Openreach were a properly regulated, free standing business, they'd have far more interest in offering better and cheaper broadband, but as things stand, VM know that most customers will be reluctant to go back to BT's shoddy and inept offer, and suffer the slower speeds.
Better still (and even more unlikely) OFCOM could mandate unbundling of VM's cable network as well as Openreach, so that third parties can offer services over cable. That would p1ss on the Cable Cowboy's chips, and I'd be delighted at that.