I think that update is coming although Verizon tends to be very conservative, like they want to be absolutely sure the update won't screw up people. So far I've seen the update have already been leaked, and even people using it on the CDMA HTC Hero.
Basically its the same update used on the HTC Hero, as the Droid Eris is just a repackaged Hero. So we know at least from HTC's end, this update exists. Will likely be pushed out of the GSM HTC Hero first then to the CDMA variants of the HTC Hero including the Droid Eris.