Assuming Howard does not re-sign, and it is likely he will in some form, the library of Stern shows is some 25 years deep. There is enough content in the can to carry both 100 and 101 until the end of time. IOW, I think the "Stern Era" will never end.
Will it be as good without fresh shows? Certainly not, but even a mediocre steak dinner is still a steak dinner, even if it's not a porterhouse. I also think the channels will suffer without Howard's sage guidance. I think they will start to do "wrap up" shows of the old shows, sort of an archaeological history rather than a daily wrap up, however, which would be a good move.
This means a lot of either live or taped Stern personalities to wrap around the old content. Stern devotees will love it. Folks probably will never get so tired of old Stern shows that the channels disappear (maybe one will) but when you create something as profound and as seminal as Howard has over the last 3 decades, it can live forever, just like Frank Lloyd Wright lives on in virtually every building designed even today and probably always will, and all contemporary jazz has roots in Miles Davis and probably always will.
"Era" is probably a misnomer, as that denotes a beginning and ending. "Milestone" is more appropriate, as that denotes a point in time when something begins but does not imply an ending.
And, BTW, there is a widely-held school of thought that SR would be gone already without Howard's influence. The things that handcuff SR are its poor audio quality for music, its being split in two at the outset then joined back together in the merger as some sort of two-headed beast that is technologically incompatible with itself, and in particular the fact that SR has to pay royalties that terrestrial radio does not. Even that playing field and bring out a dual radio, and SR will begin to thrive, with or without Howard.
And it is not going away, for the simple reason that it has lots of paying subscribers, and more of them than HBO or Showtime or DirecTV or anyone else other than ComCast cable. No one could ever find a justification to end the flow of cash, which is $3.6 BILLION with a B, annually, just counting subscriber fees and not even counting ad sales, which is also significant. The 5 major networks don't make that kind of scratch combined (and they have NO subscribers). They will soon raise rates 12%, and far less than 12% of subs will abandon ship because of it, meaning they will gross even more revenue in 2010.