Goldman forecasts SPX 3100 at end of 2019 and 3400 at end of 2020. I don't see SPX 3400 until after 2020, maybe in 2021.
Taking the other side is this guy:
Opinion: This Fed rate cut could signal the stock market’s peak
"The same school holds that too aggressive a monetary policy will lead to rising debt levels, asset bubbles and even greater wealth inequality. For instance, internationally, quantitative easing has allowed bonds valuations to soar, helped support equity market valuations and importantly, given politicians in countries like Italy and the U.S. the cover to engage in increasingly risky fiscal policy, to run up debt and avoid economic reforms.
More dovish voices will point to the many risks from abroad. But the Fed can do little to resolve these.
The risk that investors may not have priced so far is a deepening of the growing tensions in Hong Kong. In the context of a multipolar world, the protests represent a contest between two systems. In the background is perhaps the most overvalued property market in the world, the fifth-largest stock exchange and a currency peg (to the U.S. dollar) that is becoming more costly to support.
Hong Kong is a risk to the U.S. because a crisis there could push up the dollar, lead to a round of de-risking internationally, and fuel fears of a macro shock across Asia.
More broadly, the U.S. stock market approaches the Fed meeting from the wrong side in the sense that valuations are very high historically (though not wildly stretched) and corporate profit margins may be at a peak. There is also the possibility that the dollar strengthens further, hitting export-oriented tech stocks.
Overall, the risk from here is that markets decide that monetary stimulus is in the price now, with economic and geopolitical risks rising, investors begin to reduce risk through the remainder of the summer."