Update: An anonymous Sprint tipster has told us this deal will only last through April 16th - Sprint is probably trying to clear out its current stock of EVOs and soon-to-be-discontinued devices.

If you were pondering buying a Sprint Android phone this weekend, it may be wise to hold off for a couple more days - Sprint has announced to Phonescoop that devices currently offering mail-in rebates will switch to an "instant savings" model starting Sunday. That means no forms to fill out, and no rebate checks to wait for. Verizon recently canned its mail-in rebate offers in favor of the same system, so it seems logical that the US's other major CDMA carrier is following suit.

Given the announcement of the AT&T/T-Mobile merger and Verizon's unprecedented success with the launch of its first 4G LTE smartphone, the HTC Thunderbolt, Sprint is scrambling to gather up new customers before the prevailing smartphone winds shift. Will the EVO 3D and EVO View 4G be included in this end to mail-in madness? That's an unknown at this point, as Sprint only said it would be ending mail-in rebates for an "unspecified" period of time. Whether that period of time is only up until the launch of its new flagship 4G device will likely be seen in the coming weeks.

Phonescoop via Phandroid