The mod angle has been addressed so I'll approach it from the other side, of why this-or-that feature hasn't been implemented yet or whether they'll be implemented at all.
i only see 1 upcoming feauture, and im sure there are more stuff to add
I'm not sure what "1 upcoming feature" is referring to, since there's quite a few in recent blog posts, but I'm sure the Alex's primary objective right now is to complete the main story arc whose first part was released in 0.95. There's more things coming such as some more Ships to toy around with, more weaponry mainly consisting of laser missiles, and a minor revamp of faction rosters to make them a bit more distinct to fight.
like there is barely naything for the sindrian diktat
The Diktat actually has a middling amount of exclusive assets compared to average with their special Lion's Guard skins equipped with built-in Solar Shielding. Sure, Hegemony has some more exclusive assets (Auxiliary ships and XIV Battlegroup), but factions like the Luddic Church just has a handful of skins with no special properties, and Persean League doesn't even have that.
They are getting more assets next update though, including a heavily modified variant of a new Midline capital ship and a few new exclusive (or near exclusive?) weapons.
you cant colonise abandiooned space station or make one,
There's only a few pre-gen abandoned space stations that likely couldn't/shouldn't be rebuilt back to functionality, and I think only 1 of those is located in an uninhabited sector. The randomly generated stations are basically loot. Finding an abandoned station (or building one from scratch) suitable for recolonizing in the sector is a fairly interesting concept, it's just likely not a high priority item for Alex to spend time on, if he wants to at all.
more story and main side quests for each faction,
The main story line is in development for sure. Faction side stories could be interesting, perhaps once the main line is complete to a satisfactory degree.
better control for your faction and diplomacy with other factions, tech reaserch maybe.
This stuff kind of sounds like 4X mechanics. Star Sector is not going to be a 4X game, so these are definitely not planned, at least not in the way it sounds like you're envisioning them.
Increaseing your population past 6 with the cryosleep ships,
Using Cryosleepers to get through certain Colony restrictions is a fairly common suggestion. Can't say I have a good idea what Alex thinks of it one way or the other, unfortunately.
and more stuff to do in planets, so that you can do stuff there and quests, and wait for things to happen in your colnies,
Most of this is pretty unlikely; Planets & colonies are a bit of a side show. Barring basic quests (which typically has you doing something in space rather than planet-side, like freight hauling or bounty hunting), any content that increases the micromanagement required for colonies (doing things and waiting for stuff to happen) is likely to be a hard sell.
and even a epilogue of what happens after if there is a end game with lots of choices and factors like what colonies you had or how much money or income you had to decide how te life of your dude and the sector played out
Honestly, I don't personally want a big "where is he now?" epilogue once the main storyline is complete. Just a credits screen and return back to the game to do whatever once the Big Bad
TM is defeated.
Plus it would take a decent chunk of time to implement, and whether or not it can be implemented in a satisfying way for a game as open as Star Sector. Imagine getting a slide where your PC "becomes a well-respected yet ruthless board member for the Tri-Tachyon corporation" due to happening to have a friendly or cooperative rating when your only real engagement with them was doing some pirate bounties and convenient quests so you could acquire enough capital to finally push Jangala into the sun.
