Ecto-2009;150311
Yes, perhaps Steve Guttenberg and Allen Sheedy could be in again. As co-stars and not the main characters.
Sequal to a remake is a new storyline. I guess you can't call it Short Circuit 3.
Yea, you're being very confusing now.
If they have the original cast back in it, then its not really a remake, its a sequel. A remake and a sequel are very different. The word you may be looking for is reboot. Which could either mean remake, or a new sequel to bring fresh life into something.
And the reasoning you offered up (new generations aren't familiar with old films), is not an excuse to remake something. Old films exist on DVD, VHS, Blu-Ray, whatever. Re-releasing them on those forms of media is a way to introduce them to a new generation. Remaking them for the sole reason of trying to get new fans is pointless, as it will lose all the old fans in the process usually.