I guess the plot in this OVA is not so new to Detective Conan fans. Including me, I am sure everybody else has somehow thought of what could happen if Shinichi remained Conan for good. We all have our own thoughts and ideas but this is another possibility of what could happen.
Well, I think what I really got from the OVA is the impact of Conan's presence in the story. In his dream, he was able to lie to everybody and so his lie eventually became a fact, a truth. Now that Shinichi had a glimpse of what could happen if he will just hide and be Conan for good, for sure he is so motivated to take action and be Shinichi ASAP.
DL for those interested are found at: http://www.edgarluvitug.com/2009/09/lupin-iii-vs-detective-conan.html
My biggest thanks to edgarluvitug for allowing his DL links be shared ^^