Frontierland would be expanded a LOT if they tear out the Circle D Ranch and Festival of Fools arena, per the plans Al Lutz shared with us last year. But to REALLY make an impact, they should also rethink the BBQ place (nice though it is) and the Fantasyland/Videopolis Theater. That entire stretch is contiguous and would constitute about 1/5th of the park. It would make a great spot for a wonderful, sprawling E-ticket attraction like the Jungle Cruise, Nature's Wonderland or the Western River Expedition or something else. (Your ideas welcome.)
One idea that comes to mind is Eddie Sotto's old unused idea for Knott's, where a flash-flood sweeps you (in a raft or something) through the desert and through an old mining boom town -- Inside saloons with gunslingers having a shootout over the table-tops, cattle swimming around you, etc.
Personally, I think a Frontierland expansion is the most interesting growth opportunity Disneyland has had for a long time, and I wonder why there hasn't been more discussion and daydreaming here.
I know we're talking about enough property to create a whole new land, but my vote would be for an expansion of Frontierland -- Or possibly the expansion of both Frontierland AND Fantasyland. Frankly, Disney's track record with creating iconic and inspiring NEW lands has been fairly underwhelming, beginning with Bear Country in the 1970s.
On the other hand, Disneyland has done a fairly good job of adding new attractions within each land's existing themes over the years. (Star Tours, Indiana Jones, etc). So again, my vote is for the same old lands -- just MORE of 'em.
How does everyone else feel about this? I mean, THINK of it! They have the opportunity to make DL's functional space 1/5th larger! Given a decent budget, the possibilities are endless!
(I looked for an existing thread to post this in, but the most recent one FOF Area/Circle D Ranch... Frontierland Expansion or New Land was "Closed." Not sure how closing threads helps. But there's progress for you.)