More info on Blanchett’s return including PETER JACKSON’s reaction as well as casting of key roles from the book can be found HERE.
Orlando Bloom will likely be the next original cast member set for an encore. He’s near a deal to return as Elven archer Legolas. And it’s for more than a cameo.
Read more on that HERE.
As far as Ian McKellen (Gandalf), Andy Serkis (Gollum) and Hugo Weaving (Elrond)?? Those actors are no longer confirmed as being involved. THRALL WORLD previously posted they were on board whilst GUILLERMO DEL TORO was still involved as director but the source article specifically mentions they have not been confirmed since the change to PETER JACKSON as director.