Interesting

I kinda like that thinking!

As Korra is the reincarnation of all previous Avatars it is possible.

They are still their past lives. While the connection may be gone, I headcanon that Korra can still find things from her past lives to be familiar and maybe even have flashbacks from their PoV but cannot directly communicate with them.

I had a similar thought. The next Avatar could find items of importance (like Aang's staff, Kyoshi's fans, Roku's crown, etc.); and meditate with them. There could be fragments of past Avatars souls attached to these artifacts. Collecting enough fragments could restore connections.