Here's the thing, from a business perspective.... you need to bear in mind that there's two players here, the network who basically only "rents" the show (and sometimes gets to participate in some profit-sharing) and the Production Company who actually owns the show, but who is out of pocket for all expenses. As the network's share of the audience continues to drop due to all the competition from the cable networks, the amount they can afford to pay has also dropped considerably.
Many times in the last few years, the cost of producing a show has started to exceed what a network can, or is willing, to pay significantly. Unless the Network has a really sweet back-end deal, they would rather stick some "reality" show or low-cost production type show in their line-up because it is far more profitable. If a show is in it's 3rd to 4th year, sometimes the production company will lower its "rental" fee to a network to make certain they get to the magic number of 100+ episodes in the can. Once you hit 100+ then you can "strip" the show and put it into syndication.
From some of the industry publications I've read, it appears that ABC is cutting back on its comedies and changing it's Friday night line-up completely. I seriously doubt that this has anything whatsoever to do with politics. It was #13/22 shows on ABC and most of the shows below it are cancelled or likely to be cancelled (in fact, ABC's lineup is so week several of the shows ranking above are on the chopping block). If it were airing on NBC, it would only be 3 from the bottom of that networks shows and on CBS it would be 20/26. (With 2 broke girls averaging a 1.5 rating, while LMS had a 1.1 rating.) The audience for the show had declined somewhere between 8% to 12% over the last year (depending upon the source.)
Bottom line, many shows are now basically pricing themselves out of the market and I would expect that we will start to see many of the shows centered around a name-brand star to likewise be cancelled or for those stars having to accept concessions on salaries and perks.
Things have drastically changed over the last 35 yrs or so in regard to network television. Remember this: MASH's finale ('83) drew over 125 Million viewers, Cheers finale ('93) drew some 89.5 million viewers, Seinfeld's finale ('98) got 76.3 million, while by 2005 the networks numbers had dropped to the point that the highest rated show that year (the finale of Everyone Loves Raymond), only drew 38.3 million viewers. Today, it's not uncommon for even the highest rated shows on the networks to be lucky to draw 6-8 million viewers.
Even ballyhooed non-network shows like Walking Dead were only pulling in around 10-11 million last season. By contrast, LMS's audience (total viewers) was about 7 million on the average last season. And I'll guarantee you that Tim Allen was making more per episode than the top 3 or 4 cast members of WD combined. (They have a notoriously tight budget.) Looked it up, Allen was making a little less than $250,000 per episode while Andrew Lincoln was making less than $90,000 and he's the highest paid actor on the show.