As far as the US real estate market goes, I'd say it's possible that people parking their money here in even greater numbers will accelerate the current drive for luxury real estate while causing a shrinking of the middle value real estate market. You also see this in London right now, with tons of new luxury buildings being built and sold off, only to sit empty and used as a value bank. The general effect is that real estate values in general rise sharply and people are forced out of middle-value areas so that they can be redeveloped into ultra-high value areas. These are geographically centered effects, though. I'm really not sure how much it could drive the larger real estate market, which is already as hot as it's been since the crash.
Conversely, if it were investments in infrastructure, businesses, and tangible productive goods that create real world value, we could rest a bit easier.
The SV scene isn't like the dotcom days without a business plan. There's a lot of startups now that have revenue from day one, and are cashflow positive. The value is tangible in many cases (not all).
Second, I wonder what impact the tanking China economy will have on the US real estate market. Wealthy Chinese have been parking their dollars in real estate here for a while, and with the stock market seen as more risky now, I wonder if that trend will increase and drive up home prices further.