When you say it will be, it's currently not firmly planned, or even officially indicated that is will be, connected to anything but the GWML and EL. In my opinion that's very poorly connected. From a tube map perspective it'll look as well connected as Acton Mainline (i.e. unconnected). The only planned lines running through it are the GWML, the Elizabeth Line and HS2. Sure there are lines in the vicinity, but Willesden Junction is nearly a mile away, and unless they build a new bridge North Acton is also nearly a mile away. There are buses, but unless you're looking to get somewhere in the local area, that is adding significant journey time. There are a two proposed Overground stations, but right now those are a dream, there is no funding, and the overground doesn't have the capacity, or go to the Central London destinations that the tube from Paddington does.
Compare this to Paddington. It has the GWML, Elizabeth Line, the Circle line (Twice in both directions), the District Line, the Hammersmith and City Line and the Bakerloo Line. I don't see how this is at all comparable. Paddington is clearly vastly better connected, and it only takes standing at Paddington for 10 minutes to see the notion that everyone is changing to the Elizabeth line is plainly wrong.