I am curious as to who you believe to be the true descendants of Beethoven? Is it the camp of Berlioz, Liszt and Wagner or Schumann and Brahms?
I definitely can hear a lot of Beethoven's later symphonic works in Symphonie Fantastique. Particularly in the interesting textures and the programmatic elements. Berlioz was then was a major influence of Wagner and Strauss. I must admit these elements feel to me a bit contrived and detrimental to the overall form in Berlioz. However he did greatly influence new german music through featuring a recurring symphonic theme which evolved into the Wagnerian lietmotif.
At the same time I can hear Beethoven's larger coherent forms and logical progression of key areas present in Schumann and Brahms. These two do feature a lyricism not found in Beethoven. Their counterpoint is also more akin to Bach or Palestrina. However there is certainly Beethoven's stamp of the heavy orchestra particularly in Brahms symphony no 1. I also find Brahms and Schumann very good in terms of the type of logical coherency that is masterful in Beethoven.
I know that is a lot but this is a big topic. Who do you hear as Beethoven's continuation and through what elements of the music? Feel free to bring in other influences and names as well.