The Mirror of Galadriel...A clue to ROTK?

[samwise of the shire]

I went to see LOTR:FOTR for the Sixth or seventh tie yesterday and noticed two things at the Mirror of Galadriel. When Frodo looks in the first thing he sees is *Sam, then Merry and Pippin, then Legolas. The Mirror then turns to the Shire as it was when he left it, then it turns to the Shire being destroyed and *Hobbits being led away for what I presume is forced communistic labor, then it turns to a destroyed desolate Shire. Then the Eye comes up, and scares Frodo. The Galadriel says *"If your quest fails this will coem to be."
I thought of something then. If Frodo fails in his quest(which he does as he doesn't destory the Ring Gollum does)then those things he saw in the Mirror would come to be and as such I think we can expect a Scouring!!!YAYAYAYA!!
Does ANYONE have ANY speculation as to why Frodo Sees only his Hobbit companions and Legolas in the Mirror and not the others? Does THAT mean something. I thought it meant that Legolas would help in the Scouring? Because it was the four hobbits that vanquished the ruffians and it showed the three hobbit companions and no one else exept Legolas
And does ANYONE know why we have Hobbits in shackles being led to the mill?
Sam