I noticed that too. I imagine they will announce something soon. I imagine they will definitely release them in digital format. Especially with the new Movie Macabre app that was recently released on iTunes
I wouldn't worry too much. They've been consistently releasing the DVD's every 2 months. I would expect the next one to come out closer to February with an announcement probably some time in January.
And it looks like as they continue to release the DVD's they'll be pairing them with episodes that didn't air. No word on the boxsets but that may come out when all the DVD's are finally released and they simply repackage the DVD's (that's my idea at least).
A new Elvira's Movie Macabre 4 disc set will be available May 8th, 2012. Preorders are available at Best Buy for around 20 bucks. The headliner of the discs are the Wild Women of Wonga. Get your players ready! Wooowhoooo! :)