I would, but not for a while because we just had an Underground route and I think this one wouldn't be the best one to do as it's only tunnels
I tend to agree with you on that one - so maybe they could start by extending the Bakerloo line? It goes to Watford, or at least did last time I used the Underground, not terminating at Harrow & Wealdstone. There are lots of other lines that go overground as well as underground that I'd enjoy - Northern, District and/or Metropolitan to name but three.
I'm sure I was there (Stonebridge Park side of Wembley) many times until mid 80s for the snooker, although to be fair I never went further north by tube than Stonebridge Park. Why, it does terminate at Harrow & Wealdstone since then I take it? Maybe BR does the other leg now then - that would make sense I suppose.
I believe passenger numbers were the cited reason, in '82 it was cut right back to Stonebridge Park, but reinstated back to Harrow & Wealdstone in 1984. BR ran services over the Watford DC lines before and after, and Watford is still served by the Overground today.
Line is automatically driven with CBTC in addition to the tunnels provided if Dovetail Games is fine with an automated Metro System to be added ending. However if the Victoria Line is made it will be a stepping stone to how German train signaling system LZB is used on U-Bahns German and Austrian term for a Subway as their automated driverless train system. https://en.m.wikipedia.org/wiki/Linienzugbeeinflussung. There's already a CBTC with LZB U-Bahn proposed in this forum that is U-Bahn München.