If it can't match the accuracy of the Hornet in any kind of wind, and doesn't have the steam (nowhere close, frankly), then it's accurate to say performance of the 5mm is poor. It wouldn't be a 200 yard round, certainly. Nor is the 17, so many would not consider it an improvement. A bullet light enough for good speed in the 5mm would be no improvement in B.C. over what the 17 offers, and the 17's BC is no better than .22 long rifle ballpark (.130). 0.130 isn't good, quite honestly.
Low priced 5mm isn't likely. Noticeably higher pricing than the .17 or .22 magnum is. Even these are hardly cheap. A small increase in performance for substantially increased cost is probably what would occur with any revamp of the 5mm.
Look at it this way:
If the 5mm was such an obvious winner, and production and pricing as well as performance limitations were so easily overcome, someone would have tried it again by now.
So certain of high speed salability of subcalibers were some marketers that the 17HM2 was introduced shortly after the 17HMR......and flopped big time.
My guess is that the people that take the risks figure the longer range rimfire market is now saturated, and the 5mm isn't enough of an improvement to warrant the effort and the substantial cost of failure.
Time will or will not prove me wrong, but a resurgent 5mm rimfire isn't a safe bet for those that take the marketing risks.