That was probably the strongest language they could use. You very rarely want to “guarantee” anything when speaking about the future as a company. Something may delay them and they don’t want to be crucified over wording.
Horrible comparison. Every NFL team would say that, and none of them have any control over what happens.
Alleviating server stress at launch, with so many people in a couple zones, is the primary purpose of layering. Temporary population expansion is secondary, and they’ve already warned people on full realms that the queue may get longer after layering is turned off.