[RPG] list of wizard spells by level by school

First, I'd like to say that this kind of oversight and poor editing is common in the Mythic rules, and it's likely that whoever wrote the Mythic Spellcasting rules wasn't thinking about retraining spells when they wrote the feat and power. Thus, any ruling you make on this will likely be supported by at least one interpretation of the rules text.

That said, I would say that the rules as written most support the interpretation of the selected Mythic spells remaining static once chosen. In the description of the feat/power, there is no mention of changing the Mythic spells selected, and generally choices made in feats cannot be changed without specific retraining. This implies that the selection process is something that happens once, when you take the feat, and is static afterwards. Since nothing says that you can rechoose your Mythic spells if you stop being able to cast the regular version, you can't. Those Mythic spell choices become basically inert until you regain the ability to cast those spells, or use some kind of feat retraining to get a different set of Mythic spells.

Someone has reposted it on the EN World forums or you can access the Wayback Machine version which should last longer than Google's cache.

You could also just save the html page yourself (or copy out the information) so you always have a local copy.