I would say the landing page is exactly the case where jQuery is not needed anymore. Yes, it's convenient to use, yet for a mostly static page with a few XHR calls, some DOM interactions and whatnot - it's a bloat, actually. 12-16 months ago it would be a sabotage in most cases, but once it's all OK to forget about IE8 - you really can put the good ol' DOM-AJAX-animation JS libraries to rest.
From personal experience: just few days ago I've made a landing page. Focus was on mobile and performance so no jQuery, modernizr, lo-dash, and so on. We only grabbed some syntatic sugar from microjs.com so we could write $(el).remove() instead of el.parentNode.removeChild(el);, etc.
Turned out a nice, little page with all the usual bells and whistles only really needs a 12KB of JavaScript code (uncompressed). We actually missed lo-dash more than jQuery.
In age of "modern browsers'" ubiquity, and Angular/React/Ember/MV* libraries doing the heavier stuff, the support for older IEs is really the last selling point of jQuery. And that goes away soon.
Unless you're using the unversioned ("latest") jQuery version on your CDN, the browser cache hit rate will be way less than 95%. I've seen some estimates at less than 20% (can't find the link at the moment).
And for various reasons, it's not a terribly good reason to use the "latest" jQuery version with no version, unless you're prepared to deal with sudden code breakage.
> then there's a 95% your users already have it cached.
In reality, there's a less than 5% chance that your users will have the right version cached, but a 95% chance that your users will notice when the public CDN is over capacity.
React isn't really a framework like Angular or Ember. Remember that it's view only - it doesn't handle ajax calls, routing, error handling, async code, etc.
From personal experience: just few days ago I've made a landing page. Focus was on mobile and performance so no jQuery, modernizr, lo-dash, and so on. We only grabbed some syntatic sugar from microjs.com so we could write $(el).remove() instead of el.parentNode.removeChild(el);, etc.
Turned out a nice, little page with all the usual bells and whistles only really needs a 12KB of JavaScript code (uncompressed). We actually missed lo-dash more than jQuery.
In age of "modern browsers'" ubiquity, and Angular/React/Ember/MV* libraries doing the heavier stuff, the support for older IEs is really the last selling point of jQuery. And that goes away soon.
P.S. Very handy: http://youmightnotneedjquery.com/