I know you're not a huge fan of an all-TB/USB-C approach
Not so much on a desktop where the dongles can stay put and you're not losing a data port to charging. If the new Mini has 8 USB-C ports, in some reasonable permutation of 3.1 and USB4/TB4 then I'm fine.
Realistically, though, the extra cost, complexity and resources of USB-C/TB3 mean that an 'all USB-C' approach means we're likely to get
fewer ports of any kind - as evidenced by the new iMac, esp. the entry-level 2 port version.
As for USB 3 hubs in keyboards - I think that, if people wanted them, the market would have already provided (and there
are various USB-2 hub/keyboards around which probably mops up most of the demand - for a hard drive or suchlike that actually used USB 3 bandwidth I'd prefer to connect it to a top-level port).
Know what
might help? At least if we're moving to all-USB-C: An affordable USB-C 3 hub with at least 6 USB-C ports providing USB 3 only, the ability to distribute the full 15W from the upstream port and an
optional 100W power input to give full USB-C charging.
Its the biggest omission of the whole USB-C system - even the new $200 OWC USB 4 hub only gives 3 type Cs (but that's not really what it is
for).
...because until then I'm going to need the 7 ports + 3 power from my $40 USB 3 type A hub, which
also means I'll still be using a mixed economy of type-C and type-A connectors even if I end up with an all-type-C computer.