They've been meeting supply & demand, providing music & trying to match whatever demand there is. In the 1930s jazz musicians mixed '20s blues & early jazz tunes, wrote their own instrumentals/vocals, & adapted Broadway & Hollywood musical tunes, forming the initial foundation of 21st century "straight-ahead" jazz & a process for "jazzing" music.
Then, in the '70s jazz split into many streams, often jazzing other forms--mainly rock--or going in a "free jazz" vector. Even with a core of straight-ahead jazz in clubs & on jazz radio, that diversity continues & should be recognized.
Recently I've heard:
--Kate McGarry jazzing Simon & Garfunkel's "Feelin' Groovy";
--Chance the Rapper's jazzing in his nominally hip-hop "Surf" CD;
--Kamasi Washington & his band playing hardfunkbop, jazzing the many styles he plays;
--the Durham NC Art of Cool Festival presenting "jazz-influenced" music that blends contemporary music styles with jazz or vice-versa;
--Abdullah Ibrahim jazzing his musical cultural history;
--Mary Halvorson playing artjazz, telling me if it's not jazz itself, it's "jazz-influenced" (another jazzing type).
And, twelve years ago in Bucharest I heard singer Teodora Enache jazz traditional Romanian folk melodies, scatting to the timbre of the tambour. So jazzing is not just an American phenomenon.
I've had jazz educators tell me that many jazz-trained musicians are part of pop music these days, contributing--I hope--to the quality of the music. So, we're being jazzed in many ways...
So, to look for "jazz" these days in its breadth do we have to be open to "jazzed" music that uses jazz instruments, uses syncopation & swing, &/or improvises habitually? What else makes music jazzed?