A lot of these foreign investments come from China. I don't know a solution - if I had buckets of money I'd love to have property abroad (although more for living, less as investment). I don't know what restricting local investments in property would do economically, but I know the current lack of restrictions cause terrible hurt to locals.
This is exactly part of the whole deal. It's inseparable. Why would they sell you something in the first place if they couldn't buy anything back?
China has gotten very rich in the last twenty years, but it has been nothing close to an equal rising tide of prosperity. There are now uber-rich competitive with the greatest dynasties of Euro-American enterprise that want to do something with all that wealth, and particular relative to the West they have a problem with their stock market being heavily state controlled and thus an undesirable place to safety hoard capital.