Everyone can do that, it’s not even just an in-game mechanic. Portals between Azeroth and the afterlife have been set up. So all those time skip theories are wrong but yeah.
And afterlives is a bit of a meme at this point. For example maldraxxus main theme is necromancy. Necromancy. In a spirit realm. I mean, why? Giving spirit a physical form in a spirit realm?
The short version: as far as lore is concerned, unless a future patch says we go back to Azeroth as part of the storyline, we’re trapped in the Shadowlands.
As far as gameplay goes, naturally they aren’t going to cut you off from everything else.
“Quickly Skully, my faithful servant, we must commence the ritual to raise the dead!”
“We are dead, sir.”
“Excellent! My unlimited power frightens even me!”
I mean, technically, we open a portal from Oribos to Stormwind/Orgrimmar right away. Then we start even getting visitors that never went through the Maw. The citizens of Oribos are even all “What have we done? Now we’ve got uncontrolled immigration!”
But, didn’t Bolvar pretty much say that going to the Shadowlands was a one way trip? Sure, we’ve got reinforcements coming in, but I don’t think they’d have mentioned it being one way if it wasn’t going to matter in some manner later.
I believe when he said that he meant the Maw, but that could just be my own extrapolation based on how you can travel between the other realms, but what happens in the Maw stays in the Maw (at least until we show up).
“We need to to cross over and bring back our abducted leaders but you won’t be able to come back. Nor will they…um…excuse me…Hey Carl! Carl! Who wrote this recruitment litature? It is awful”