About 20 years ago I was in Portugal and remember it was a TGV project that didn't take off. It was supposed to connect to Madrid I believe. I imagine that politics and money created this issue.
We could already have good connections with Alpha Pendular trains, it would be a matter to extend and improve existing infrastructure, not build a new one from scratch.
Same goes for the never ending story of the new Lisbon airport, it will make very happy everyone involved into its construction.