Its intrinsic value whole will probably top out at about $1000. At least that's what Mazda charge for the core. That said, you can't just sell the used motor to Mazda so you're probably looking at selling it to somebody for half that (or less) so that it's actually worthwhile to them.

It might be worth it to part it out. Many of the parts don't wear out quickly they should be easily re-used (UIM, LIM and associated valves, front cover, AC compressor, water pump, TB, OMP, exhaust manifold, etc). It's also possible that some of the internals will be useful but you won't know until you take it apart.

You could always go the Top Gear UK route and clean the keg up really well so it can act as the base for a glass-top coffee table. Even better if you can omit one housing and one iron so the internals are visible.