It sure would be nice as part of the 2024 roll out for DnDBeyond to quickly add some conversion tools. I think having such tools available would go a long way to reducing a lot of the frustration I'm seeing discussed with converting mid-campaign to the new rules. Here are two examples of the tools I'd love to see:

1. A tool to easily convert a character from 2014 to 2024 rules, (where applicable as obviously there are some classes that don't have 2024 versions). Said tool should automatically back up the old character, (by creating a copy if user's account has room for a new character). If unable to convert some parts of a character it would be nice if the wizard could highlight the differences to allow choosing from the available 2024 options, or to abandon the conversion. Yes, all this can be done manually, but it's clunky and time consuming and sometimes results in a lot of frustrating wasted effort if you find something about the switch that doesn't work with the rest of the campaign. 
2. A tool to easily copy and convert homebrew rules. For example, one of my player's monk is using a homebrew sub-class. We liked the core 2024 rules updates, but could not select the previously created homebrew sub-class until I as DM manually created a duplicate of the earlier sub-class selecting the 2024 Monk to start. Took me a while to figure that out and we were all close to ignoring 2024 rules all together despite some things we really liked about them. I suspect there may be a similar issue with Homebrew Feats (though I have yet to run into that) where it would be nice to easily quickly convert or somehow mark a homebrew rule as applicable to 2024 classes, feats, etc.