I think it's important some form of the Tomorrowland theme and name remains, since it's an essential part of the framework that Walt Disney put in place, and has helped design and influence every Magic Kingdom style park that's come since. In the age of Galaxy's Edge and IP overlays, it'd be a huge mistake for Disney to start ripping away what makes Disneyland "Disneyland"
My answer is a blend of a few of the choices. Obviously, the idea of doing a "Tomorrowland" based on today would be a huge mistake given the rapid pace that technology is expanding and improving... America is gonna look way different in 20 years.
The best solution, and one that Disney utilized in the past is the Jules Verne themed Discoveryland/Tomorrowland '98. Obviously, the '98 refurb was botched for a number of reasons, but I imagine if the budget had been proper (minus the Astro Orbitor Location/moon rocks) that would've been a huge success similar to Fantasyland '83 and Tomorrowland '67.
At this point, Disneyland is rooted in nostalgia. My favorite solution would be to go retro... embrace the "Dreams fuel the future" and highlight visionary ideas of the past. In this case, build an updated Tomorrowland '67... a peoplemover with a new Progress City model updated to be relevant to 21 century audiences. Gut Star Tours and put in a proper dark ride that's rooted in a romanticized depiction of science that's quasi "edutainment" instead of Adventure Thru Inner Space. Bring back the Rocket Jets in their proper location, in a similar style to what was there before.
Reconfigure the Space Mountain Concourse. Gut Magic Eye theater and turn it into restaurant seating. Bring back the Space Place windows (where FP distribution is now). Move the Space Mountain entrance to accommodate this. And most importantly.... put a new state of the art attraction where Redd Rockett's half a**ed Pizza Planet is right now.
Gut/Demolish the carousel theater and either dream up a new animatronic/theater style show like America Sings- or put in a new state of the art attraction. My vote? Build the original Journey Into Imagination using modern technology. Bring back Baxter to lead creatively.
The Autopia should stay... but needs a new fleet of electric vehicles. Reconfigure the track to take up far less space utilizing more elevation changes and a shorter ride time. Ditch the Honda ASIMO nonsense. Use the new space from decreasing the space taken up by the track, as well as the old motorboat area to add an "Aladdin's Magic Carpet Flight" style E ticket dark ride or a "Jolly Holiday" Mary Poppins dark ride.
The submarines should stay... but should be reimagined into a more serious "journey into the depths" style theming that's more adult and scary than both the original submarine voyage, and the Nemo iteration. Include more realistic marine life, and have it be based on going into the depths of the ocean that are unexplored and un mapped to tie in with the "Tomorrowland" ideal of conquering new frontiers through the progression of technology.
Buzz either needs a thorough update, or should be replaced with a new attraction.
The best part of this is that it can be completed in phases as Disney becomes willing to budget new funds to the project. Reskin the land and rebuild the PM to start, the conquer the other attractions in phases to prevent the closure of half of Disneyland.
A land that's both a love letter to the Disneyland the "purists" long for, as well as a respectful update and progression of the ideals put in place by Walt would be a welcome addition after Galaxy's Edge.