It sounds like a very fun theory, but very unlikely to be true.
Sure, it is a very interesting link to draw between being able to become any Pokemon and containing the DNA of all Pokemon but the fact that the abillity to become anything is very generic which doesn't give Ditto the need for an explanation for the power and the fact that "containing the DNA of all Pokemon" and "being every Pokemon's ancestor" are descriptions Mew didn't get until Gen II and not even at the same moment, make any plausible link look like a combination of coincidence, an imaginative mind and good writing. I find it very easy to believe that when they scripted mew into the game just before the deadline they taught letting it learn all TM's was cool and unique and that also letting it learn transform looked even cooler (not only learning all the moves but being all the Pokemon) or transform was just an addition to make it plausible that it was so rare, people just don't know they found mew as it is a copy.
And that brings me to another thing, we all know that mew was scripted into the game at a very late state. At first I thought that fact alone would prove there was no connection but then I thought of the fact that mewtwo was scripted into the game much earlier and there where also already hints about mew even though he was not to appear. So yes mew might have been created before ditto, but there would be no reason not to mention the connection because it makes ditto that much more of an interesting Pokemon.
Concerning the breeding stuff, they just saw in Ditto the potential to make this new and somewhat difficult and annoying process (especially for kids) easier. And concerning the move transform uniqueness, it isn't the only signature move from generation 1 which is still exclusive.
It may, just may, be a link they created later (I still think they would have hinted at it, no point in keeping it a secret), but defiantly not a connection they had in mind when creating those Pokemon.