In the almost 60 hours I've played, I don't think I have ever gotten bored or annoyed with the narrator. I don't think I will either, if my initial binge is anything to go by.
That said, given that this is just the tip of the iceberg, I don't think we will see another narrator voice.
There is more to a performance then just digitally modifying the voice. Watch Dogs: Legion attempted something of that sort for it's multi-protagonist design. I heard the result was mixed, when it comes to believability of the voice.
Even if it's functional, a question would be if digital creation of multiple VOs out of one would be worth a weaker base VO performance, which is a must have, if that same voice is supposed to be bland enough to be moulded into whatever sound engineer desires. I also doubt it's as simple as switching couple settings and calling it a day - with a massive amount of VO, like Baldur's Gate3, how much would they gain by having audio engineers work on it, instead of setting up few extra recording sessions.
Wormerine puts it best. I have a very small amount of experience with VA work and I can tell you that this work can be more than you might think. Not only are you likely going to have to do all the lines again, but you are also likely going to have multiple takes for each as you try to find what the director is looking for, and then the audio engineers have to clean up/adjust the audio, and people on the software side have to put it into the game while making sure they all trigger like they are supposed to. Throw that on top of everything else they are working on currently (character models, quest/item implementation, AI tweaking, etc.) and that can cause the game release to be pushed further into the future. More variables you add into the game, the more things that require double-checking lest they break. That takes time and money. Money, while likely ample, isn't infinite. They also have a set timeframe (possibly) they want to release the game, so having this extra narrator would be redundant in the bigger picture, best left as possible DLC.
Long story short: My bet is that we won't see another narrator.