It's a pretty good idea, you know.....And AF ( and LH ! ) have been offering through tickets using rail services for quite a while now....With AF, this includes cities such as Tours, Brussels, etc and others where there is an existing TGV line but no air service....With LH, I believe that these are between Frankfurt and cities such as Stuttgart and Cologne where the journey time is very simlar by rail or by air...
In the land of wine and cheese,although the rail network is not perfect, it is streets ahead of most other European countries because it's still owned by the state....And as mentioned above, investments / subsidies / etc to improve rail networks are permitted by Brussels ( even encouraged ) so a little French tete-a-tete over a nice lunch and I'm sure that the French government will help AF by developing an infrastructure which would suit them both - one asset, two markets - and provide yet more competition for those annoying British and Irish newcomers to domestic air services here....
On the other hand, state ownership means that rail services are one of the main players in the French national sport - going on strike !! So the risk to AF if they do get into bed with SNCF or whoever will be reliability of services....Not really good
PR if the service is even slightly unreliable....
But after all, why duplicate the effort and cost of moving people from and to CDG from cities such as Strasburg, Lyon, Bordeaux, etc, when the time for the journies by air and by rail are so similar...And with a TGV station already at CDG2 and no need even to leave the terminals to reach it, there is tremendous potential for cost savings for all involved, not to mention the environmental goodwill that this would be seen to generate....
And question - does a through ticket for an air / rail journey become cheaper if there is no ' ticket tax ' for the part of the journey made by rail ?
So not a new idea, but interesting to see if this will become a full blown operation to destinations outside of France - London using joint services with Eurostar, perhaps, would seem eminently sensible and practical for pax and also free up slots at Heathrow for yet more SkyTeam codeshares....