Cars Land, Mermaid, TSMM and WoC were 75% of the $1.25 billion DCA got. The rest was Buena Vista Street and some placemaking for Paradise Pier.
Keep in mind... my idea of what might happen involves keeping Indy/Muppets
I would think $2 billion could get:
TSPL ($80 million)
Pizza Planet relocation ($25 million)
Great Movie Ride upgrade ($70 million) - $150 million
Fantasmic revamp ($50 million) - $200 million
New daytime/nighttime parade ($50 million) - $250 million
Cars dark ride ($100 million) - $350 million
Monsters Inc dark ride ($100 million) - $475 million
relocated Laugh Floor ($50 million) - $525 million
reskin of HITSK for Up/Bug's Life ($25 million) - $550 million
One Man's Dream moved to Main Street, USA... replaced by Pixar Story ($25 million) - $575 million
B&TB replacement along with an additional theater ($75 million) - $650 million
Mermaid replacement ($50 million) - $700 million
Disney Junior upgrade ($25 million) - $725 million
Incredibles E-ticket using Twister ride system ($250 million) - $975 million
Gusteau's TS ($50 million) - $1.025 billion
Mos Eisley Cantina TS ($50 million) - $1.075 billion
Star Wars theming ($75 million) - $1.115 billion
Star Wars speedbike coaster ($175 million) - $1.29 billion
X-Wing/TIE spinners ($50 million) - $1.34 billion
Millenium Falcon walkthrough/M&G ($75 million) - $1.415 billion
Star Tours facade upgrade ($25 million) - $1.44 billion
Indy upgrade/revamp ($50 million) - $1.49 billion
MuppetVision upgrade ($35 million) - $1.525 billion
Muppets C-ticket dark ride ($50 million) - $1.575 billion
Muppet Mobile Labs/Electric Mayhem Streetmosphere ($20 million) - $1.595 billion
Swedish Chef/Gonzo reskins for Mama Melrose's/old Pizza Planet ($50 mlilion) - $1.645 billion
Sunset/Animation placemaking ($55 million) - $1.7 billion
New parking garages/reworked backstage ($300 million) - $2 billion
While I'd love to see a Mystic Manor clone added to Sunset, Toontown where Animation Courtyard/the space by RnRC is, and some theming upgrades for RnRC... those aren't essential.
Giving the park some thematically distinct areas (Star Wars/Indy, Muppets, Pixar, Disney Animation/Toontown, Old Hollywood) without the 'you're on a movie set' pretense would do wonders for making DHS a worthwhile park.
If New Fantasyland cost $425 million and Pandora cost $500 million, surely all of that could happen for roughly $2 billion. Especially if Backlot Tour and LMA being demolished isn't included in the cost.