Well, there still isn't. It's not really a new line, just an indirect connection via existing high speed lines that takes over 8 hours. I don't think that's gonna be very competitive with air travel which takes less than 2 hours.
Apparently the highest average speed rail line in the world averages 318 km/h and the straight line distance between Paris and Berlin (through Belgium and Luxembourg) is about 875 km, the time could be about 2.75 hours, which wouldn't be too bad.
In reality the lines wouldn't be able to go straight and you might want to avoid going through any countries other than France and Germany. The best case scenario would probably be a little over 3 hours, which still wouldn't be too bad.
The route is surprisingly Z-shaped mostly due to geography, since the Ardennes lie on the direct line. Also the development of the rail network in either country took no account of the other country.
That's further north than the direct line - I know I have fond memories of hitchhiking Brussels->Aachen with my girlfriend in the 1970s. Direct Paris/Berlin train needs to go along the Sedan/Bastogne axis that is not very flat.
Apparently the highest average speed rail line in the world averages 318 km/h and the straight line distance between Paris and Berlin (through Belgium and Luxembourg) is about 875 km, the time could be about 2.75 hours, which wouldn't be too bad.
In reality the lines wouldn't be able to go straight and you might want to avoid going through any countries other than France and Germany. The best case scenario would probably be a little over 3 hours, which still wouldn't be too bad.