okay, i only got to about page 10 so forgive me if I am repeating something...
I believe one of the dragon riders will be a Martell. Specifically Arianne.
When House Martell submitted to the Targaryens, King Daeron II married the sister of the then Prince of Dorne, Maron Martell. Maron then married Daeron's sister
Daenerys. So not only do the Martell's have the "required" Targaryen blood, but specifically the blood of a Daenerys Targaryen.
Arianne was intended to marry Viserys. I believe she may be the rider of Viserion.
Viserion's color is pale and gold, the same color as desert sand.
Prince Doran plans to ally with House Targaryen.
I may be stretching things, I know.
I have no idea who the other may be, but I don't think it will be a Lannister.
Is it likely Dany will allow Jaime to ride a dragon, the murderer of her father? I think not.
Tyrion, maybe. Since he was never truly accepted as a Lannister and he killed Tywin, Dany may not view him as a true Lannister either. And all that talk about wanting a dragon is a bit
too obvious for me. If he does join up with Dany, I think it will be as an adviser. Tyrion always seems to get shafted, I don't see any reason for that to change any time soon.
Jon is a likely possibility, if he is Rhaegar's son. Didn't Dany have a dream of Rhaegar standing over a baby saying he is the one of ice and fire or what not? I believe Dany will know when (and if) she sees Jon if he is Rhaegar's son.
(I also believe Ghost is the embodiment of one of the old gods. He is the exact coloring of a heart tree after all. but anyway...)
If it is Jon, he will ride Rhaegal.
Arya, I don't know...it just doesn't fit for me. She is in somewhat close proximity to Dany (I think) and I don't believe she will become a Faceless Man. I don't think she'll ever let go of the fact that she is a Stark of Winterfell.
Meh, who knows? It could very well be characters we haven't even met yet.
I don't think Dany will ever rule Westeros. I think she's going to die defeating the Others.