There are several strange assumptions in the article. One of them is that "growing hashrate is a sign of adoption".
This isn't the case in my opinion. Growing hashrate is caused by price/profitability expectations. But miners don't care about "adoption". They care only about their income, and this is currently not driven by transaction fees (which are about 1/20 of the regular block reward).
Another assumption that isn't necessarily true:
More users mean more holders, and holding increases demand and therefore price.
More users mean also more sellers. In fact, "hodling" is based on the expectation of future usage. In a "mature" Bitcoin market, hodling will decrease and not increase. This could even mean the price could go down a bit, but what I would expect is relative price stability. The circulation speed would be higher, and thus also liquidity, which means that order books are always full on both sides and neither panic nor FOMO will reach the levels we've seen in the past.
Growing hashrate is also only natural because it's an indicator for technical progress. From Moore's Law you could deduct approximately, that if the Bitcoin price is stable, hashrate should grow about ~50% per year - if it's less, then miners are making losses (e.g. if the mining market overheated).
We see that in 2018 this was the case for some time: while there was a strong increase at the start of the year (driven by the still very high Bitcoin prices), later hashrate decreased again, and at the end of the year it was only slightly above the values for April.
In 2019, however, price increased, at $7000 it is currently approximately two times the value of January ($3500). Thus, the expected hash rate increase isn't 50% but up to 200% (price * 2 + 50%). This would mean that the "expected value" for today (December 31) is 35 EH/s (January hashrate minimum) * 3 = 105 EH/s. We're currently slightly lower than that (at ~95 EH/s), so miners are almost exactly following the expectations we can deduct out of Moore's law.
So no, hashrate isn't a reliable indicator of a future bull run. It is more based on past price movements. Miners normally can't predict the price better than the market can.