I think at the moment, if we are thinking about resources and recycling then... probably yes, I do think it’s sustainable. I think it is because our retailers are set up ready for Christmas [4], and along with the predictability of high consumption it means a sudden surge in resources usage is prepared for. The resources are made ready, early enough and made available in high enough quantities for this time of the year. Recycling plants and landfills sites know about the increase in waste that they should expect this along with the increasing awareness about why we should recycle more means that the stresses on our resources will decrease. More and more people are aware of 'tips' to help them out around Christmas to reduce the resources they use so it is easier to be sustainable [5].
Depends on what you mean by a changed world. If you mean a world where everyone is thinking extremely strongly about sustainability and wouldn't buy a sheet of paper without

... Yeh, damn the do-gooders! I want my lights :)
http://www.youtube.com/watch?v=rmgf60CI_ks <- Really recommend the link 1) Compilation of Waste Statistics from various sources: http://www.reducetheuse.co.uk/Page/Waste/Wastefacts.htm
2) Bradford Council Environment Page: http://www.bradford.gov.uk/bmdc/the_environment/waste_management_street_scene/waste/recycling/christmas/
3) Official Waste Statistics: http://www.wasteonline.org.uk/resources/InformationSheets/ChristmasRecycling.htm
4) Retailers Advice about Christmas: http://www.utalkmarketing.com/Pages/Article.aspx?ArticleID=16056&Title=How_retailers_should_prepare_their_e-commerce_platform_for_Christmas
5) How to have a Green Christmas: http://www.eartheasy.com/give_sustainchristmas.htm