I can't think of any. Donna Summer found another direction that year, the Bee Gees "temporarily" retired and the movie, "Can't Stop the Music" absolutely bombed for being completely out of step with the times! "Celebration" was a huge hit in '81 but was not considered disco.
And this is why we have the Billboard archive at Google Books. From the Disco Top 100 Chart in the July 5, 1980 issue (as close to mid-year as I can get). I'll just list the stuff Top 40 played:
1. SOS Band: Take Your Time (Do It Right)
5. Jermaine Jackson: Let's Get Serious
20. Irene Cara: Fame
21. Diana Ross: Upside Down
55. Brothers Johnson: Stomp
56. Spinners: Cupid
69. Gary Numan: Cars
70. Devo: Whip It
81. Lipps, Inc.: Funkytown
I think Gary Numan and Devo might be open to debate, and certainly things were winding down by 1980, but stuff was still happening.
There was still a disco chart in the first week of July, 1981, as well (a bit of a surprise to me), and the stuff that crossed over to Top 40 was:
5. Rick James: Give It To Me Baby
19. Quincy Jones: Ai No Corrida (well, KFRC in San Francisco played it)
30. Stars on 45: Stars on 45
99. Frankie Smith: Double Dutch Bus (again, KFRC)