1. Horror Ambient.
This could have been still available at least in Wasteland/Burnt Forest biomes as a slightly remixed and refreshed version.
2. Some of the old zombie models.
Simply nostalgia kicks in.
3. The Bee.
It is kind of strange but the mutated bee never felt way too off for me at least in the Wasteland biome.
4. Caves.
Devs should have rather implemented caves as POIs instead of randomly generated undergrounds for better optimization perhaps?
5. Climbing zombie.
Since there is one that jumps very high, I guess the version of the mutated one that climbs (not a ceiling) only the walls wouldn't be way too off I guess.
More variety for the future, like mini-boss events, and zombies with abilities, strengths, and weaknesses. Special Infected could instantly infect a player if he comes in contact but are easy to eliminate instead.
6. Huge wandering horders. Actually, why not keep them in more demanding biomes except for Forest?
7. Speed boost in vehicles as mentioned above with better car batteries.
Could be extended into handling at certain terrain, steering responsiveness, and so on perhaps someday in the future.
8. More variety of biomes.
I believe that Devs might expand biomes into sub-biomes very easily, mainly for aesthetical purposes. Older alphas had more variety of biomes.
Some bread for thought.
The Forest biome might be split into:
Forest - dense forest as it is now,
Plains - meadows/farm fields, open spaces in general,
Mountains - rocky mountains with cliffs and valleys,
The Desert might be split into:
Semi-Desert environment as it is now with cacti and vast plains,
Sandy desert with burnt ground and open spaces,
Canyon areas with lots of cave systems.
Snow biome might be split into:
Snowy Liveable Areas as now,
Frozen Lakes with huge ice sheets/cliffs and cave systems in the ice,
Snowy High Peaks with valleys.
Westland biome might be divided into:
Radiated Zone - very difficult to survive without end-game/special equipment not obtainable in the early game and a mythical Hub City - should be like a holy grail and final destination with an end-game Trader, POI, or sth that would mark the end-game)
Burnt Forest - like it used to be,
Rocky Area - dark as depths of hell with canyons, mountains, cliffs, and craters filled even with lava, enshrouded in thick fog - very unpleasant zone and difficult to survive in without mods but with excellent loot.
I would love to discover more in the late game.
9. LearnByDoing - as an optional game/progression mode for 7DTD so players could give feedback in search of alternative solutions.
10. Old small POIs without loot crates.
I believe only trader missions should generate loot crates into POIs. I would rather have randomized loot crates with their random location in a given POI, or 3 possible locations. After 2000h spent in the game things are getting too obvious
11. Spawning into Wasteland and being blown by a random mine just at the edges of the biome, or being chased by a zombie dog after 5 min into a game...
Just kidding.