I’m of a similar mind.

My time online is limited, and if Threads ends up having the most interesting stuff then that’s where I’ll spend my limited time. If I can follow users from Threads over at mstdn.ca then I would very likely stick with the Fediverse to get the best of both worlds. I’m mostly a content consumer so I go where the content is.

Also, I don’t really think Threads and Lemmy are a good match, if Threads is more a Twitter substitute then I think Mastadon is a better match (and all micro-blog class Fediverse platforms). So I suspect not many people will use Lemmy to follow anyone/thing from Threads, defederating them won’t have much practical effect.