You buy investment RE for one reason: the expected flow of future benefits and you're willing to pay a certain amount of money to receive said future benefits. Depending on what your goals are as an investor, that'll determine how much present value you place in the future amounts.
The benefits usually come in 3 forms (operating CFs, sale proceeds CFs, and tax benefits). Using a sensitivity analysis you can do your best to determine what your expected returns could be for a particular property.
Maybe the big time investors developing, purchasing or refinancing the Class A properties that cost $100M+ (which will be hit first and hardest IMO) have a better understanding of future changes in their markets than us? Or maybe they don't and they just have more risk tolerance and/or can live with smaller returns on their capital.
When doing analyses I assign three scenarios to the stream of benefits. Each stream involves a best case, worst case and most likely set of assumptions for the operating cf/sale proceeds. From there you can formulate an expected IRR and some measurements of risk. If the project presents too much risk and not enough return to sufficiently compensate you, then the deal's a no go.
That's in a nutshell the basics of how I analyze a property. Yeah, the amount of deals that pass the smell test have been reduced because of higher prices (but that doesn't mean a "bubble" is occurring, or if it is, when it's going to "pop"). What's seemed to become the case is there are deals with an IRR I can live with but when you look at the sensitivity analysis, the amount of risk has been higher than before (because they usually involve more intensive value add to achieve what I want).
It just might mean that the days are slowing/over of buying stabilized properties for cheap and relying on minimal management/guaranteed large mkt rent growth to give you your big return.
Then again it depends on your investment goals, the property type, the class, the location, your intended hold period, your level of debt, and what actually occurs in future mkt conditions, etc. Saying you 100% refuse to invest in things today in general makes no sense. So it's really an impossible thing to answer or predict and if you could you'd be a billionaire.