RENFE (national railroad company) had no competitors until very recently, they opened the market just months ago. I am hopeful the new high speed companies (i.e Ouigo) makes the market much more competitive and lowers pricing in all tiers. Still, for same price and roughly same time, I always prefer using the train to the planes.
This is happening in France, too. I'm not too optimistic on how this will turn out.
What we've seen here is TrenItalia starting to serve one line, Paris-Lyon (and then on to Milan). The issue is that this is, by far, the most profitable train line in France.
If competitors only get in on the profitable lines and leave the others to the national company, it will probably not end well. Because it's my understanding that profitable lines used to somewhat compensate for the others, SNCF was able to provide a somewhat dense service. If this goes away, they'll either have to reduce (or even stop!) the less profitable service, or the State will have to step in with even more subsidies for those lines.
There's a lot of talk in France around "public service" and I think that things like good rail service, especially in the era of "climate emergency" is important for a State to have. Instead, we're now getting new bus routes - yay diesel!
