SNCF Voyageurs having secured pretty far ranging rights in Italy and Spain, plus the expansion of the Ouigo brand, probably gives them a tad more latitude on losses within France and other captive markets. They are in a pretty strong position now for the next few years regardless of the loss of their monopoly rent on Eurostar.
Also, look at Eurostar London's utterly outrageous prices. They are massively out of step with domestic French TGV prices on comparable routes, even if you add a premium for Tunnel charges and border control and security. They have many years of notice of the new entrant, and are being very successful at pushing up the price level well in advance. This gives them much more headroom to drop prices back down as soon as the new services starts to defend their market share.
Also, look at Eurostar London's utterly outrageous prices. They are massively out of step with domestic French TGV prices on comparable routes, even if you add a premium for Tunnel charges and border control and security. They have many years of notice of the new entrant, and are being very successful at pushing up the price level well in advance. This gives them much more headroom to drop prices back down as soon as the new services starts to defend their market share.