Re-use Old URLs for Updated Content
For pages which are updated annually, or when a new product model is released, it makes more sense to keep the same URL and update the content, otherwise you may see the old page ranking instead of the new one as it has better ranking signals. If you need to keep the old content, you can republish it on a new archive URL.
Deprecated HTML Doesn’t affect Rankings
If you’re using out of date or incompatible HTML, it won’t affect the rankings for the page.
No Good Solution for Reactivating Pages
If you have pages which expire but are reactivated after a period of time, there isn’t really a good solution, but you can use a Sitemap to tell Google about URLs which are now active, and use the unavailable-after meta tag.
Expired Content Can be Redirected
Even if a page has been unavailable for some time, then you can still redirect URLs to pass on the authority.
404 Pages Crawled Less Than Noindex
For expired/removed content, John says that Google prefer a 404 as it results in less crawling than a noindex.
Redirect Expired Pages to Alternatives or 404
Out of stock/expired pages can be managed in a variety of ways. If there is a relevant alternative product, or a category page with good alternatives, a redirect is OK, otherwise a 410/404 is best.
Migrate Replaced Products to New URLs
If a product is replaced, you can move the old product content to a new archive URL, then put the latest product on the existing URL. This allows the same URL to rank over time, and always serve the latest version of the product, and allow the historical product content to be kept.
Submit Expired Pages in XML Sitemaps
You can submit an XML Sitemap with expired pages to help get them removed from the index more quickly. It’s best to put them into a separate sitemap so you can see them separately to other indexable URLs.