That's basically correct. There is a certain item rating level that once an individual item slot goes over that rating, it starts only getting expertise for its bolster (no more "PvE" stats). As the item rating continues to rise, you get less and less expertise until eventually bolster doesn't get anything from that item. The result should be that in the best PvE gear, you are somewhere between the "introduction bolster" level and the top end PvP gear in power. You would still be better off swapping to PvP gear if you have it, but you aren't terrible.
Also worth pointing out that this system works on an individual item basis, so each slot itself is bolstered up independently of all of the other slots on a character, so slots can give more of a bolster bonus than others if you have a really powerful item in your chest slot, as an example, but a really behind the curve implant.
Thanks for responding. However, if I'm interpreting your response correctly, that means that top end PVE gear would receive none or next to none expertise. This, as you put it, would put us somewhere between "introduction bolster" level and top end PVP gear in power, but only on damage output. The damage reduction provided by expertise cannot be replicated by any PVE stats, and thus PVE gear would still be far inferior to PVP gear. Now, I don't think any PVE'er would try to argue that their gear should be equally viable in PVP as PVP gear. However, I don't think it's unreasonable to expect it to be at least competitive by performing as good as PVP gear a tier below it (i.e. DG, which is equivalent of EWH, performing at WH level in PVP). Thanks