"A" says something.....
"B" repeats it.....
"C" says it must be true, I have multiple sources who agree.....
sigh..... internet logic.....
All that said, If Canon came out with a non "L" 200 to 600 F6.3 lens, it would probably be about 1 1/2 times the price of the Sigma and Tamron offerings and with a 3X zoom range it would probably be sharper than it's 4X range competition..... but that is at F6.3, a speed that will play havoc with all but the newest Canon AF systems, so that speed is HIGHLY unlikely...... Make it a F5.6 non "L" lens and it's at least 1 1/2 times the cost again...