I personally doubt all but 2 and 4. A slight redesign isn't unlikely, however i seriously doubt they will redesign the mac pro, so changing the acd so it doesn't match its 'natural mate' is unlikely. i love both the mac pro and acd designs currently, but i have few doubts that apple would replace them with anything less visually appealing.
price drop? only if they aren't redesigned.
portrait? nope.
isight? likely a waste for their target market (i'd much prefer no such thing), but if they only add a few $ to production and the end user, fine.
23" panels have been phased out (rather unfortunate really since 23" @ 1920x1200 more closely matches the pixel pitch of the 20" and 30"), so a 24" is a likely replacement.
In my perfect world we'd see updated enclosures to match the tweaked mac pro cases (black anodized or same case/new grill with different grate pattern in black/glass? unlikely, but as long as the acds aren't glossy like a chinless imac i'll be ok with it), and price drops so a 24" would cost me ~650-700 without any discounts.