If this is pretty much only "self" as an object type, then it sounds an awful lot like what the existing "Replace object" option does. If you want to swap SpriteA for SpriteB, "Replace object" lets you do that for a chunk of events in a few clicks.
As 
piranha305 touched on there are tons of edge cases with this and it will probably be complicated and difficult to implement. Given we have hundreds of feature requests and limited development resources, I think it's hard to avoid the conclusion that if this is only like "Replace object" but with lots of extra of difficult and awkward situations that will be time-consuming to sort out, then it would be better to just use "Replace object", or find some other way to tweak "Replace object" to work conveniently with a new workflow.