My first story, The Neallys, was pretty long. About 70K words over 5 parts. The number of parts was based on changing POVs.
When I finished, I got the urge to update so along came parts 6 and 7. I'm thinking of just carrying the story forward every two months or so, reflecting the passage of real time. The story's been well-received.
I may do it for myself anyway, but I wonder if readers will be interested.
I'd say go for it!
If you take a look at the top lists for each category, the long-running stories often have chapters that are high rated... which means that there's an audience for longer and more in-depth storytelling.
Three Square Meals is just over 3 million words and still going at chapter 126. It's a serial, all focused on the same characters, so I decided not to break it up into separate stories.
Some people balk at the idea of starting a story that large and others love getting stuck into a massive tale. You're getting great scores so far, so I think it's a fair bet that your fans want more!