Playing out 2023 is the best solution for the Chargers and Austin Ekeler
Austin Ekeler may not be the best market option via trade
Ekeler isn't the only perceived big-name running back who's potentially available on the trade market, a factor that in my opinion further lowers his value. Derrick Henry's name was floated during the combine in Indianapolis. Dalvin Cook may end up being a cap casualty as the Vikings are looking to get off salary.
With a Henry trade, it would likely be a contending team taking a shot on a one-year rental to try to boost their chances for a playoff push. The key factor here though is of course that the Titans are looking to offload Henry in his age-30 season. There's no pressure to extend Henry at time of trade despite being scheduled to be a free agent next year simply due to the nature of the position at that age.
Cook's contract on the other hand technically runs through 2026, but there are ways to get out of it cap-wise after both the 2023 and 2024 seasons when the guaranteed money is paid out.
The point is this: teams might value more premium running back production via trade, but they also want flexibility. Henry and Cook are just two examples of trade options that would give similar or better production in comparison to Ekeler while not having as much of a long-term commitment via extension.
That doesn't mean Ekeler won't be able to get a contract extension per se. But if other teams around the league are choosing between running backs close to or at that 30 mark, they're going to go with the ones that are less expensive and less of a commitment given similar production.