I think this inflationary pressure is likely to come from the supply side, rather than from the demand as you rightly pointed out i.e. wage will likely to remain subdue as unemployment is likely to remain high: unless Biden manages to push through the minimal wage increase. The supply side stems from the shutdown of businesses and as the economy picks up, reduced competition allows businesses to become price setter and this is more so in the service sector. Prices of many different commodities are also increasing. Needless to say, the seepage of increased inflation will have many iterations through economy and the potential positive feedback should not be discounted.
Ultimately, I think the key factor is the amount of money in circulation in the economy i.e. M2 and velocity of M2. Though velocity of M2 is very subdued but on the other hand, there is so much more money(M2) slouching around in the economy to the extend that the effect will still lead to high inflation. Jerome P says that M2 has no relevance now to inflation but I prefer to stick to the older theory that it does matter.
BTW, Biden still has $3T of infrastructure spending in the pipeline.
My calculation says it is 6% by Dec 2021 but I happy to settle for 4-5%.
