Flight to the Ford
They made Frodo too sick to ride Asfaloth on his own, but if they hadn't, Glorfindel and some others could have encountered Strider and co. in much the same way how Haldir was handled later: only G.'s name is mentioned. However, he would have to get more scenes in TTT and ROTK, even as someone whom Elrond commands.
I believe Haldir is only about as important as Glorfindel in LOTR-proper, as both perform similar helping functions (though Haldir didn't cow several Nazgûl, of course). We could have gone without him too, had PJ kept the scouts nameless. Because PJ and co. planned to kill him later, he got some "face time". Right?
Direct consequences
Aragorn has no love interest. No parallels to Beren and Lúthien. No "drama" regarding the choice between immortality and love. On the other hand, no "Arwen's Fate is Bound to the Ring" subplot, and no girlfriend to taunt Aragorn with in the scene where he uses the palantír.
Éowyn
This looks accurate (I hope). My memories of the TTT/ROTK films are more than a little hazy (as with these specific book-details), but I think this wasn't conveyed well, and they emphasized the romance angle. Since Aragorn doesn't already have a love interest, the original point could be kept.Wikipedia writers wrote:Éowyn became infatuated with Aragorn as a great captain of men who would lead Rohan to victory. However, Aragorn ultimately rejected her, pointing out that she only loved the idea of Aragorn as a great leader and warrior who would restore Rohan and her lonely life, but not Aragorn himself.
Note: Dec. 23 - changed "as important than Glorfindel" to "as important as Glorfindel".