Huge risk of obsolescence. Not that that really bothers me as I have a number of wierd vehicles. But you have to be prepared to wait for weeks (months?) for replacement anything. Not just major components. But little things like door handles and trim pieces? As Billibob mention, glass? And lack of ANY garage that will know how to even start repairing it. Are YOU going to "wrench" on it? What about software glitches and recalls? Will it have a full service manual? Do we even know if it will be OBD2? If it is will it have a profile on any ELM32 app like Car Scanner? Will it have specs for the emissions inspections for the donkey garage down the road to look up? Startups are great. But car startups? Wait until (if) 3rd or 4th gen is a thing. And have a very big wallet and lots of patience.
Glass = flat and designed to be replaced at any tractor shop that can cut glass. Way more easily replaceable than most modern 4x4s with the exception of the Wrangler which uses the same design or the same reason (at least originally; these days the reason is more likely about staying true to an aesthetic)
Repair = Factory Service Manual is digital and (will be) online, freely available to owners and private shops. This includes a 3-D CAD-It model that actually walks through the repair steps. They are partnering with Bosch service centres which have a robust network worldwide, and are targeting this vehicle to be repairable by even the shadiest of shade-tree mechanics in the middle of the bush with bailing wire, chewing gum, and some cuss words.
OBD2 = Yes, because that's required to sell a vehicle in most of the developed world, and this vehicle is being sold world wide.
Profile = Unlikely to be necessary, because the vehicle is supposed to have the minimum technology necessary to be legal for sale so generic codes are probably fine (For instance my motorbike is OBDII, does not have a profile, but the generic codes always read fine on the 4 different code readers I've used; Gren is likely to be the same)
Software glitches and Recalls = No idea on mechanical recalls, but the design of this vehicle means "software glitch" is more likely to be a "turn it off and back on again" solution that won't leave you stranded, as opposed to a bad sensor on the third manifold from the right that measures microounces of bat guano in the exhaust is somehow so critical it triggers a limp home mode. TBD if they've achieved this but it looks promising so far, and so this may be less of a concern than it would be with other new vehicles.
Emissions specs = Yes, part of the repair manual and necessary for the "global platform" approach that Ineos has taken (i.e. it's the same rig in Canberra as it is in California).
Still more detail to come, but I've been following this project pretty closely - press releases, protoype tour events, live streams, etc. and the challenge with all the details of this vehicle is that they've answered a lot of things in a lot of different places -- so many that it's hard to find specific answers when seeking them sometimes!
As for the OP's question regarding parts availability, there's sort of two dimensions there: The first is, how easy will it be to conveniently pay someone else to fix your Grenadier? And the answer is "it depends on how many they sell". The second dimension is "How easy will it be for a determined individual to fix the Grenadier" -- the kind of person who is willing to weld up a U-Joint of a pair of 12V batteries with some jumper cables is likely to be very happy with the reparability of this vehicle relative to what else is available new on the market. For that category of person, I think fixing the Grenadier 10 years from now will be no problem. For example, I'm planning on getting one (though I may have to wait - life has had some curveballs for me) and I've already got a plan on what I intend to do if/when the B58 becomes more trouble than it's worth because an engine swap in a vehicle like this makes sense to me. I wouldn't do that in my current truck or a typical daily driver vehicle. I think for folks like me, who do see this vehicle as something different than what else is available, the Gren should be pretty maintainable and serviceable and able to go the distance because of the philosophy behind the design - robust, user serviceability, as simple as they can make it -- which Ineos appears to have largely delivered on.
