Using Would instead of Will in Future Perfect

Dear Friends,

I would like to how "Would" can be used in future perfect as a modal verb.

For Example.

Analysts predicts that world population would have risen considerably by 2010. (Prediction can be wrong, so using "Would" instead of "Will" means this sentence is less directive than the below one which is using "Will" )

Analysts confirms that world population will have risen considerably by 2010. (here analysts are confirming the likelihood of world population being increased by 2010).

But both of them are pointing to future. Are these sentences correct ? Can we use "Would" in future perfect in this way to mean something less likely to happen in future.

Or consider this:

Day "begins" at about 09:00 after 4 hours of sleep. So after doing the customary check on emails and stuff like that, I pack up all the rest of the stuff I have (computer being last, obviously) and then leave home.

So on the way to the airport, I finally manage to get Kara's number (to wish her a happy early birthday since I would have left by that time) through Linda -> Connie -> Bonnie. (I guess, speaker was not very sure that he would have left by that time, so he used would have left instead of will have left). Is my understanding correct ?

Another Example:

My company will have allocated 50 shares for me by Jan 2007, but it's of no use for me as i would have left the cmopany by that time. (Here again speaker is not sure whether he/she would be out of the company before Jan 2007, other Will could have been used instead of Would have).

Please let me know whether my understanding is correct ?

Regards

Sabya