Keep in mind, that most cars are only produced in a particular form for a few years. Body styles, features, driveline options, safety updates, etc, all change every few years on most models, so almost ANY car that is approaching ~10-15 years old, even if the same "model" is still being made, likely hasn't had something exactly like it produced in at least 6+ years.
I was still able to find parts for my 94 rodeo easily enough. The tough to find stuff would be tough to find for any car that old... I was running into issues like weather seals that can't really be "salvaged" and nobody provides anymore.
I believe that as the H3 transitions from the hands of its "first generation owners" to the hands of "enthusiasts" (in some cases, no change of ownership will occur for this transition), we'll see continued support for these vehicles in the aftermarket/parts/etc.
I'm not too concerned.