There would have to be quite a bit of negotiating with the cable programming networks, which typically want the broadest possible carriage they can get. Offering more-affordable tiers of service necessarily would limit carriage of many channels.
Some Wall Street analysts reportedly have warned the cable industry could harm itself by continuing to raise prices well ahead of the rate of inflation. Of course, some will speculate that the floating of "affordable new tiers" might also be a negotiating tactic by cable operators in advance of contract renewal talks.
Both cable operators and programmers are aware that most people watch a dozen or fewer channels, no matter how many are available. The problem is that it is not the same 12, from one person to the next.