I think Fox stated that
Alien would be a candidate for BluRay release later this year. However as for
Aliens or
Alien 3 both apparently require significant work before they could be considered for release. Given that Fox are doing little other than recycling their D-VHS lineup so far I wouldn't hold your breath.
Going a little OT it does make me

- these new formats are supposed to be a step up from DVD. Well for the Alien saga the last release we saw was the all singing all dancing "Alien Quadrilogy" boxset. Surely we should be looking for something similar for the first high def release? Rather than half hearted, singleton, theatrical cut only releases?