So SNCF iDBUS is fighting with SNCF TGV/Eurostar for customers. With the train the fastest 1 i can find from London to Lyon is 5 hours traveltime. With the bus it is 15,5 hours, but only 14. 1 must not be in a hurry.
SNCF is worried that they will lose business to long distance buses in the future. So their iDBUS project is designed to deter competition from private companies before it even starts. It may seem wasteful to compete against yourself but it is widely used tactic in business. In the UK, competition on local bus routes is allowed and Stagecoach compete against themselves on very profitable local bus routes in Manchester using older buses with cheaper fares branded 'Magicbus'. They have used Magicbus elsewhere in the UK over the years.
At the moment, it is only allowed to travel totally within France on a long distance bus service on international services, so for example iDBUS is not allowed to run a service between Lille and Paris only. It must continue outside of France, for example to London or Amsterdam. The main competition at the moment is from Eurolines as they now carry domestic passengers on their many international routes in France.
Full deregulation like Germany is expected soon.