In October, 2016 I removed a few thousand old reviews that were more than three and a half years old. I did that partly so I could compile call lists of people who did not have recent reviews. The results were wonderful and we manually called many people as well as doing auto-calls to many people for getting reviews. However, Google decreased the amount of clicks we were getting from them by 18% as a result of my discarding old reviews.
So, I feel compelled to put many of the older reviews back online. I am not sure if I will put all of them, or filter them out. But, I will put them back on, perhaps little by little. I want to see how Google responds when I put the four year old reviews back online. Then, I want to wait a few weeks before putting the five year old ones back.
Our readers do not value reviews that are more than two or three years, and Google rewards us a lot more for newer reviews. However, the old ones do carry weight, particularly because there are/were so many of them.
So, you can look forward to some of your antiquated reviews being put back online. But, no guarantees!>