I can't think of any culture with a observance longer than the 40 days of the Christian Lent. Our culture has a yearly cycle in which everything has its place, and if we start singing about snow in the fall, we lose our ability to appreciate that aspect of creation even as we start effectively subordinating other holidays as part of some dream version of an uber-festival which probably can't handle the pressure and will inevitably disappoint. If someone wants to claim some value to prolonging its religious aspects in this manner, then they should note that the liturgical calendar already has events during October and November which have their own purposes. With the exception of the Methodist Kingdomtide, churches generally observe it for only a few weeks, and while as is the nature of celebrations of majority religions this one has taken on important secular functions as well, I still think we should heed that wisdom.
UPDATE: While we're on the subject, people are now observing both Diwali and Eid al-Fitr. Note that Ramadan is only one month while Diwali is five days, though presumably with a great deal of lead-in.