Erm, no they don't
The whole point of legally binding contracts is to ensure that agreements remain water-tight regardless of circumstance
There are really only 2 options available to the PL here:
Option A is to refund the TV money, which would be an enormous financial blow given that match day revenue has ceased everywhere
Option B is to fulfil the obligations of the contracts and resume the campaign when it is deemed safe to do so
My guess is they will go with option B.
Option B is more nuanced than you suggest. The contract is for a set number of games in a set number of competitions.
If by playing out the old season, you lose as many, or more TV games in the new season, everyone loses.
At the simplest level, a TV company that has paid for nine PL games in the 19/20 season that are not played, simply has the first nine of the 20/21 season instead.
Because the Euro 21 competition provides a hard backstop to that season, the longer the hiatus , the more TV games in 20/21 are compromised. Already it is hard to see how the July CL qualifiers will be played on time.
On the up side some pretty innovative solutions to play games and one off competitions are possible if a full 20/21 league campaign proves impossible.