I'm thinking about a range in lightyears same as years since changes on our planet could be detectable from such distance, from where one of fast moving automat

I'm thinking about a range in lightyears same as years since changes on our planet could be detectable from such distance, from where one of fast moving automated probes economically could change trajectory toward our system by next slingshot, and comming at such speed at such time - if that speed does make any sense regarding other parameters: could we estimate or guess the cases from where then how far and how often those could go (the sizes of theoretical dominiums) and the time till next similar (but nothing about different efort) visit could happen the soonest (if the first one noticed could happen so fast, if it could transmit back..) - in case we could be not sure about that one, if it wasn't routine or not accidential.. ? (even if just only to be aware of possible scales and terms..) .. and when we will make our next intertellar probes, couldn't we make them be navigating opportunistically and trying to come back (not to confuse the universe for ethernity) ?