I am running two full nodes from my home. I have calculated that I can personally also support much larger blocks from my home. However I am in the global minority with such good connections. In terms of most people not bothering I think that is already the case, I am only running my full nodes out of altruism after all. Most people do not run full nodes anyway, I do not actually have a problem with most people not running full nodes, it was never the intended configuration for large scale deployment after all. So over the long term I would expect most full nodes to be hosted in data centers and I do not really see a problem with that as long as the timing aligns well with adoption which would help counteract the problem of node centralization.
Any realistic "calculations" will have to involve how many people do you expect to deal with the kind of burden and spurts/outages that a node puts in your network so long you have it set up in such a way that will help more than hurt the P2P network.
So this is not easy or tractable at all.
What we know for sure is that nodes are dropping steadily toward dangerous numbers, even including situations like yours and mine which means the numbers are inflated (2 in the same home are less significant that 1-node-home, VPS nodes also are less helpful for the network in terms of decentralisation).
Current average bandwidth with approx 750KB real block sizes mean 150-200GB of monthly bandwidth usage, peaks during node propagation that will stall your connection for seconds (spurts of blocksize * maxconnections which should be at least 5 to be solid, in reality 8+ would be recommendable), that makes gaming or videoconferencing pretty much a non starter already unless you stop the node (or worse, throttle it worsening latency).
And that is now, not 8MB or something very drastic like that for January being suggested for BIP101 and 8GB down the line.
There's also using 50GB+ for the blockchain currently, as pruned Core doesn't currently support wallets and won't for a bit more.
Most people are already out as is.
Check out
https://www.reddit.com/r/Bitcoin/comments/3p5n9c/number_of_bitcoin_nodes_is_at_a_6_year_low_if_you/ and this is mostly first-worlders speaking there.
Also, the node conversation is just one effect, there's miners also suffering latency and orphan rates that might force them to soft fork or feather fork creating a mess in the mining space, because regional clusters might start to appear and make large chain forks common.
When pruning support is finalised, and the major propagation optimisations are improved, then at that point 2MB seem possible and probably more, but not just because we like the number but we start deploying and observing that the transition is working safely.
And when I say that 1MB is already large I mean it, because it's already pushing people to run nodes in a way that isn't helpful but harmful, with low maxconnections under 8 and even under 5. And we have reasons to believe many are running in VPS and belong to much fewer people than numbers suggest. We might have NXT style attacks soon.
