Though it's a unique, strong, lightweight bike, it is pretty expensive and it does have very poor range due to the small battery, so I imagine sales have been lackluster, and that continuing to manufacture is wouldn't make financial sense.
They don't even have listings in the archive for the Titanio, on the PT site. The Scorpion series was similar, but not made of Titanium, and much lower priced. I found a link to the Scorpions on the PT site, but they are not listed on the 'Ebike' page.
They were 2012 bikes, which is a very long time ago, given how things have changed. Prodeco is finally getting around to mid-drives, which has to be a big part of the future. They don't seem to have anything for S-Pedelec, as well.
Sometimes I think Prodeco wanted to start building higher margin bikes just at the time the direct Chinese stuff opened up, like the Crowdfund bikes. They are going with the Bafang mid-drive, the integrated frame version. I think that would be a better deal, but now there is a $2500 Haibike.