That means Busch will become a free agent on Wednesday, but Stewart-Haas seemed to indicate on Tuesday that the two sides could yet agree on a new contract:
Busch, 39, has had a solid if unspectacular season. He won the Daytona 500 and sits 14th in the NASCAR Cup standings. He was also the 2004 NASCAR Cup title champion.
For his career, he has 29 career wins and 127 top-five finishes.
As Pockrass noted, both Joe Gibbs Racing and Hendrick Motorsports could both have openings next season. But Stewart-Haas Racing's decision to not pick up Busch's option likely has as much to do with an unresolved sponsorship deal with Monster Energy, which sponsored Busch's car the past two seasons but hasn't yet decided if it will pick up a two-year option for 2018-19, per Nate Ryan of NBC Sports.
Even Busch recognized that factor in June:
"I don’t have any worries. I know that I deliver for the team. Our performance level is one that shouldn’t be in question, winning the Daytona 500 is special, but performing week in and week out, the deliverables that I bring sponsorship-wise that comes into play.
"I know that they’re working with NASCAR, Monster Energy is trying to sort out issues with NASCAR… so there are a lot of moving parts, but I don’t feel any fear whatsoever. I actually feel very confident in the sponsorship that I bring, Ford Performance’s involvement with Stewart-Haas and how I’ve blended in with this team. I feel great."
For that reason, Stewart-Haas Racing's decision to not pick up his option but still suggest he'll be back with the team isn't a contradictory development.