Right now the network has <7000 nodes, a number that has dropped from almost 30K in the past few years. [0] The blockchain is <30GB and a node can expect to handle ~15GB/day of bandwidth. [1] You will also need at least a gig of RAM, preferably more. The UTXO is 500MB (which needs to be stored in memory).
So what we know is that despite the relatively low requirements of running a node, we are bleeding them faster than we can get new ones. People claim that storage space and bandwidth getting cheaper will solve the problem. Given past performance of the node landscape, that statement does not hold weight.
So what are the consequences of all this? Well, the node landscape will centralize very quickly as the bandwidth and storage requirements far outpace what most would be willing to provide the network gratis. Universities and large payment processors will be the only ones who can afford to run full (archival) nodes. Pruning and all that will help, sure. But in order for Bitcoin to remain true to its decentralized roots, a distributed node landscape is vital. If everyone isn't validating everyone else's transactions we have a big problem (imo, of course).
