Sadly I fear, it will never actually happen.
Unfortunately, Britain has degraded to either sycophantically idolise grungy tattooed football oiks, soap opera "Stars", and supposed singers.
Anything much else, including sensible pursuits, immediately acts as a magnet to the health and safety brigade, Nimbies, interfering busybodies, feverishly quoting EU regulations and the army of Lefty-Liberal nutters, waxing lyrically about "Quality of Life": whatever that actually means.............
IMHO Formula One, thanks to the benighted Poison Dwarf, epitomises the core realities: nothing whatsoever do do with its true wondrous roots and no longer actually a branch of motorsport, generically, but rather, a product brand in its own right with one sole objective: viz, to earn the bloody dwarf more billions so he can waste this on his latest trophy arm candy and his slapper offspring.
Practically, with such a saturation of cars, dwellings and businesses, there is not much left on which to hold any meaningful event.
Even, as we know now, circuits and stadia are under increasingly hostile attack.
Realistically, no chance of holding any event such as Mille Miglia, Targa Floria, or even Mannin Moar or Mannin Beg, anymore.
The cost of liability insurance would be prohibitive: even where an area wanted to hold such event.
Still, in memory and nostalgia, I can treasure the fact of the club (TEAC and other clubs) rallies I participated in, during the early 1970s; on public roads: at night; and all apart from areas prohibited by the then authority, the RAC (in conjunction with the M. of T), on narrow back roads and "Yellows".
Now, they were bloody fun and harmed no one.
P.S. You can view some movie footage of the Mannin Beg here: all around the houses, Douglas, I of M.
http://www.britishpathe.com/video/the-mannin-beg