The Monitor series has not been discontinued. It was discontinued at one point and replaced by the TSI line. Then they brought the Monitor series back but it's ONLY sold at Newegg. I called Polk to get this information because I wanted to make sure for myself. I own the Monitor series and think its a great speaker line for the money. Great value. If you go to Polk audio's website and look up speakers by series. You will see that there are two different Monitor series.
Ah, thanks for the clarification. My impression was that the TSi line had completely replaced the Monitors (both recent lines), since if you go to the Polk site and choose Products/In & Around The Home and then either Home Theater or Stereo & HiFi from the submenu, they no longer list either Monitor line, just LSiM, RTiA, TSx, TSi, and R/T/M.
In a way, that's sort of the same deal with the Klipsch RW-12D subwoofer - the Klipsch site lists it as discontinued, but they've apparently been continuing to sell them through Newegg for several years now since that happened.