I'm French and many friends and family would love to take TGV on holidays but have to ride by bus (search "cars Macron") or by ridesharing (Blablacar) due to the TGV prices.
SNCF recently re-launched some quite old trains under the low-cost "Ouigo Intercités" brand, because demand for cheap-but-slow transportation is more and more popular. I took one from Nantes to Paris this summer (many hours longer than by TGV) and will prefer it next time too. I could fit my bike for free there (vs 10€ in TGV, where I also usually have to disassemble beforehand).