I'm all in favour of an expansion, would be great! I'm sure if you surveyed players, they would all say the same. It's a bit like getting a petition to keep the local pub open- 99% say they are in favour of it. 80% say they will use it. 10% actually use it, it loses money and closes down.
As I pointed out earlier and echoed by Kevin, smaller bits would be much more likely to happen. An entire expansion would need a budget running into several millions as well as 1-2 years lead time, plus advertising, recruitment, etc so $10-$20m US Dollars as a bare minimum. To recoup that sort of cost needs sales of 1m copies. Let's face it, none of that is likely unless someone supporting this voting has very deep pockets. Is one of you called Musk? Until someone comes forward with some concrete proposals, a petition isn't going to get anywhere. Just look at the history of online petitions to see how little effect they have on gaming companies generally. Money talks.
Additional dungeons in Tyria could be relatively easy using only Tyrian skills (Codex coding allows skill restrictions, so coding is there), Nm and HM exist, so it's then a question of what might drop from the end chest and then making the dungeon so you cannot SC it.
And the very real issue is that 99% of players don't even know this site exists so you aren't going to get very far using this site. What you need is to push it using social media and build up a following backed with some hard cash and advertising spend- then you might get the company's attention.