I expect we'll start the 4.1 beta in the next couple weeks. I can't say when we'll have the frame-by-frame improvements, but we'll try to do it early on.

@Syneos The 4.1 beta has started and it has the frame-by-frame improvements! Region and mesh attachments have a Sequence checkbox. Works like this:
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Note you don't need to set an image path, for example if the attachment was named right-wing instead of right-wing01. If your images have zeros before the number, specify the start/end numbers with leading zeros, eg 01 instead of 1.