There's no direct workarounds for readers that I know of. I guess third party apps could do something about this if the core Masto team isn't, but I don't know of any third party apps addressing this either.
On the other hand, there are plenty of workarounds for writers, basically switching to a server that has higher character limits. This allows long threads to be entirely within one post, which means Mastodon would display them as an excerpt and a "read more" link.
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