I respectfully disagree with the assessment from that other user I quoted that Ernesto won’t develop into a major hurricane. They're coping very very hard.
Even though Ernesto started as a broad, less organized system, I think we're seeing the potential for rapid intensification (RI) if the core starts to consolidate and the pressure begins to drop significantly. The broad circulation might have started with a mean around 1008 hPa, but that doesn’t mean we can’t see a sharp gradient form quickly if conditions favor it, as you mentioned.
In similar past cases, storms have surprised forecasters by undergoing rapid strengthening once the core became better defined, even from a less organized state. So, while I understand the cautious approach, I’m still leaning towards a major outcome if Ernesto can tighten up its core and take advantage of the favorable conditions overnight.
Let’s see how this plays out—either way, it’s going to be interesting to track!