The World Championships will be held in the Swiss city of Basel between August 19-25.
Momota and Akane Yamaguchi gave Japan their first ever sweep of the men's and women's singles titles on Sunday, raising Japanese hopes a year out from the 2020 Games.
Yamaguchi, who is ranked world number four, defeated an out-of-sorts Tai 21-9, 21-15 in a little over 30 minutes at Jakarta's Istora Senayan Stadium.
The duo reigned over the sport for more than a decade and have only relinquished that hold in recent years as their powers waned.
Lee, who spent a total of 348 weeks as world number one but lost six world and Olympic finals, wept as he called it quits months after fighting off nose cancer.
The comfortable 3-0 victory sets China up for a tournament decider against top seeds Japan or Indonesia, who play their semifinal later on Saturday.
Thailand will play hosts and hot favourites China in the last four of badminton's prestigious mixed-team world championship in Nanning.
Rising star An, who is ranked 50th in the world, roared back to defeat Tai 14-21, 21-18, 21-16 in 66 thrilling minutes in the Chinese city of Nanning.
Chow and Lee were 19-15 down to Ashwini Ponnappa and N. Sikki Reddy in the second game, but roared back to win it and take Malaysia to the cusp of the quarters.
The top seeds are bidding to win the mixed-team world championships for the first time, but a major shock was on the cards when the Japanese went 2-1 down.
The 36-year-old former world number one's absence is a severe blow to Malaysia's hopes of making an impact at the Sudirman Cup, the world mixed-team championships.
Michelle Chai, general manager of the Badminton Association of Malaysia (BAM), said Lee -- currently ranked 113 in the world -- would not play in the championships in Switzerland from August 19-25.
Luck, however, ran out of him and his under-14 partner Austin Togi as they lost the doubles final.
Akane Yamaguchi became the first Japanese to win the women's crown with an emphatic victory over China's He Bingjiao.
In the women's draw, Japan's third-seeded Yamaguchi stunned top seed Chen Yufei to book her place against Chen's fellow Chinese He.