Ember is not Backbone or Marionette, both of them are stagnant. Ember’s actively maintained and improved with 6 week release cycles and LTS versions.
Ember on frontend is what Rails is on backend: less fashionable, opinionated, mature, and still useful when you value long-term app consistency over ecosystem hype and new JS framework of the month.
Htmx is a rebrand of intercoolerjs, which is just as old as react etc.
Tanstack is just an alternative layer ontop of react or solidjs. You're fundamentally still using them. It's just a diffent implementation for eg routing or state management.
So no, none of those could be considered fotm like the grand parent insinuated.
And that's ignoring how both tanstack and htmx are also over 5 yrs old, respectively. Even under these names.
Ember on frontend is what Rails is on backend: less fashionable, opinionated, mature, and still useful when you value long-term app consistency over ecosystem hype and new JS framework of the month.