I don't know if this is possible or not but I like the idea of being able to highlight posts that are either critical information or the start of a good debate.I get what @GadgetGuru is saying about some threads being intimidating. If I can't be near the boards for a few days because of work or something, I fall behind real quick and can take quite a bit of time to catch up.
The UOR Expansion, Potter Coaster, and 4th Park Threads are all at or around 400 pages. I think a good solution to this "problem" (and this is just my personal opinion) is to let threads like Potter continue since that ride will be open next year, but to close a thread like the UOR Expansion thread and create a Part 2, with the first post being a summary of all the concrete, factual information we currently have. I actually think this is also a very good time to do that as well with the recent filings on the land.
We have split threads in the past (Hogsmeade, Diagon Alley). The Diagon Alley - Part 2 thread was at 424 Pages in 2014 when we created a Part 3. The original Hogsmeade and Diagon Alley threads look like Brian had to cut them in the merger due to how old they were and their size.
That's just me though. It comes down to what @Brian G. thinks is best.
That way if somebody is about to start on a 200 page post, this can skip from highlighted post to highlighted post for the headlines.