I realised I hadn't seen a post about this- there was a better article with pictures of carriages undergoing refurbishment but I can't find it. Text has been through Google Translate. Article is here, translated text below (as per rules).
Summary: CP have bought 51 coaches (not Talgo) from RENFE including sleepers and couchettes. They're negotiating regarding access rights- these remain in place for the Sud Express which was officially a CP train that used RENFE stock anyway, whilst the Lusitânia to Madrid was a RENFE service. The article mentions going beyond Hendaye to Paris, but that seems unlikely, I suspect it'll remain as it was with a transfer to a TGV there.
Summary: CP have bought 51 coaches (not Talgo) from RENFE including sleepers and couchettes. They're negotiating regarding access rights- these remain in place for the Sud Express which was officially a CP train that used RENFE stock anyway, whilst the Lusitânia to Madrid was a RENFE service. The article mentions going beyond Hendaye to Paris, but that seems unlikely, I suspect it'll remain as it was with a transfer to a TGV there.
. Immortalized in books and films and in the memory of those who had the opportunity to try them, the Sud-Express trains, which go from Lisbon to Paris, and the Lusitânia, which makes the same route diverting to Madrid in Marina del Campo, were disabled because of the pandemic. Now, they may be reactivated by Portugal.
According to “ Expresso ”, the Spanish secretary general for Transport and Mobility, María José Rallo, admitted in early March that the two trains leaving Lisbon might possibly return to activity. Although the Spanish railway company Renfe said that the decision has not yet been completed, the progressive withdrawal of night trains at the expense of high-speed trains - which are said to be more profitable - may denounce the opposite. This opens up the possibility for Portugal to recover and manage Sud-Express alone.
"What is being studied by the Portuguese Government is to understand if it can put that connection in the public service contract", CP's director of Maintenance and Engineering, Carlos Barbosa, explained in a webinar on the Douro Line.
Among the 51 carriages that Portugal bought from Spanish neighbors, there are some that have bunk beds and that can be combined with other sleeping carriages that CP already has to do a new service. The idea is that there is an intercity that connects Lisbon to Vilar Formoso, from there to the border between Spain and France, in Hendaya, and then go on to Paris.
This whole operation should not be difficult, since, in the case of Sud-Express, only the carriages were Spanish, everything else belonging to CP. Regarding Lusitânia, although it was fully operated by Renfe, the Portuguese company will be able to “venture alone, after having recovered the rolling stock”, as explained by the specialist in transport economics, Manuel Tão.
Although these are hypotheses for the future, the Government has been trying to reach an agreement with the Spanish side, so that the new Lisbon-Madrid connection, which will be made from Sines to Elvas and should be ready in 2023 / is restored, 24. With this change the travel time will be reduced to five hours.
These issues could also be important if we think that by 2030 the European Commission wants to reduce air traffic because of pollution and noise, so the alternative could be traveling by train.