MOST of what the Flash is capable of jQuery can do that too...
plus jQuery has its own advantage of being light and its integration and interaction with HTML directly...
forget about falsh games for a while.... just consider flash based websites
only for website designs and their interaction i am thinking jQuery + AJAX is VERY ENOUGH... if i quit flash and stick to jQuery & advance in it....
AGAIN forget flash animated movies and games... and ignore stupid flash animation requirements by clients... and don't think about it in terms of that jQuery can't do Frames.. think about the final product that the frames provide...
Most users don't really care about flash, really. You can indeed do pretty much everything with a nice library + effects such as JQuery.
However, JQuery cannot do natively graphics and other fancy stuff that flash do. But you can find some functionalities in other projects like Raphaël, which uses JQuery, etc.
The bottom line is that as long as you can make something that will attract users and retain them, most client won't care what technology you're using. Until HTML5 is embraced by all major browsers, this will remain a personal choice. Personally, my choice is and will always be JQuery over Flash.