I'd love to visit wherever you decide to build your life size Autobot City,
and it would make an awesome theme park
It would be a shame for these very GREAT ideas to go to waste. If you wanted to make a toy that big, for example, you could go generic like the Autobot Ark playset, that didn't directly infringe Hasbro/Takara's intellectual property. There's a fine tradition of third party products (across many toy lines, think of the generic Lego type products you can still interface with actual lego) that are designed to be compatible with another toyline, but not in direct competition.