I agree, adding CW makes sense, and even PBS. However, I have always believed that PTAT with AutoHop was all about Dish getting some kind of leverage with the big 4 who historically want the most $$$ for their content, and I mean the O&O's they own. Dish seems to still have good relations with Tribune (TV now in instead of Broadcasting--the new reorganization over at Tribune confuses me) and so such an AutoHop threat seemed no necessary.
One problem with PBS as part of PTAT is how will Dish handle the DMA's with multiple PBS stations, and we are talking some DMA's have as many as 5 true PBS member stations. somehow, I have a feeling legislation may prevent Dish from putting any PBS stations in the PTAT. However, if PBS were smart, they would ask Dish to be including in PTAT as this could increase their viewership numbers.
One other reason for not adding any more stations to PTAT may be a technical one. Is 4 the limit to how many local stations can be recorded off of one tuner. By that I mean I has played around with seeing how many locals I could get on one tuner OUTSIDE of PTAT, and I think I hit the wall at 4, but I'm sure someone else on this Forum had the really informed answer.