I guess they'll never go for this but they could do something like select 1% of buyers at random and pay them (or refund product cost) to write a meaningful review with pictures with updates at fixed intervals so the product is evaluated throughout its intended lifespan. Perhaps with some pre-filtering to improve the likelihood that reviews will be useful and accurate (eg "spent more than $10k on amazon", "billing address is shipping address", "previous reviews were voted as useful" etc)