The adaptive tessellation was already a procedural model of sorts, at least the warping between one mesh configuration and another was. The way that mesh was turned into a progressive one in the first place is a procedural process, nobody did that by hand.
Trees are a great example, they've been procedural for many years now in some cases for obvious reasons. Any foliage, in fact - especially placing all those grass sprites!!
Any other scenery items, such as a stone wall or a house or a bridge etc. would benefit from some proceduralisation (e.g. exact placement, colour and condition of constituent stones in said stone wall). These can still be hand tweaked after the effect.
Any kind of randomisation of content effectively involves proceduralisation. Games like the Signal from Tolva use procedurally generated loadouts for enemies. It's more procedural and not just purely random, because some effort is made to create a cohesive look if nothing else.
Materials shading is effectively procedural; e.g. PD didn't paint the carbon fibre onto the cars, they just lined up the coordinates and scale for the material shader to do the rest.
On that note, many materials now are designed as combinations of layers of different procedures - PBR is a procedure that alleviates some of the painstaking work of colour matching, shading and other artistic mixing / blending of colours and materials on screen, and opens up new tools for different kinds of artistic expression, depending on how you "tune" it.
Photogrammetry is one big mathematical procedure that takes e.g. aerial photographs as its inputs and gives something like the coursemaker environments as its output.
Obviously, as far as content goes, we've got things like the course generator, but we could possibly also get a livery generator, championship / career generator, racing series (regulations) generator etc. etc. There's a lot that could be done, but it will take a significant amount of time to tune properly, but once in place and working will be highly valuable.
Still: be very cautious about equating "procedural" with "random", as it doesn't have to be. Take the demoscene, much of it is procedural (in some cases from an embarrassingly small filesize), but it's the same every time (demo) because it is at least partially generated by fixed mathematical processes at runtime instead of being entirely stored pre-made. This applies to the visual content, the music, the animations etc. All of it.
In that sense, procedural generation also has (always had) substantial usefulness in performance optimisation, by trading different resources off against each other
And, as a final note, all of the platform graphics calls, for example, are procedures. One of the things that made the demoscene so striking is that they often made their own procedures for drawing to create visuals that just weren't available via the "standard" APIs (e.g. DirectX) and their own workflows that serve their purposes, rather than the same old editing tools everyone else was using (e.g Unity). This is getting harder to do these days, though.
People often say that procedural generation is the future of gaming, but the reality is that it is already its past and present.