“IF” this passage is speaking of the judgment of “nations” and how they treat either the Jews and/or Christians, then it is speaking of the chastizement/punishment that comes to nations who fail to embrace the children of God, I think.
“IF” this passage is speaking of the judgment of individuals and how we treat the less fortunate, then it is warning of the age-to-come (from God as ordered by God) chastizement/punishment that comes to those who are selfish and do not even see the needs of those around them, much less be moved with compassion to meet those needs, I think.
“IF” this passage is a warning to the Jews concerning their treatment of the followers of Chist, then it is a warning concerning punishment from God that would come to Israel which culminated in the destruction of Jerusalem and the Jews being scattered further among the nations, I think.
And it is entirely possible that Jesus spoke in such obtuse language so as to enable several diverse messages to be heard through the one passage, like a diamond that breaks light into diverse colors through its facets, a multi-faceted message!
The language of punishment is meant to instill fear and change. It typically either highlights the worst possible scenario, or as is in this case, the punishment is vague but scary. The unknown aspect of punishment adds to its fear level, for those who need to be scared into obedience like little children.
Personally, I find this passage very convicting. It has challenged me to not be so selfish, but to see and take action to meet the needs of those around me. And historically I can see how nations that treat badly either Jews or Christians end up in a bad way. And of course, the Jews as a nation did reject Christ and Jewish believers resulting in the destruction of Jerusalem and terrible oppression by the Romans.
This passage is not a legal treatise on punishment, but it is a prophetic call to repentance filled with metaphorical and relational language. To take this passage and then try to use it to prove one specific view of punishment is, well, to misuse this passage I believe. This passage was not meant to teach specifics on the punishment of sin in this life or the life-to-come; it is meant to illicit positive change, repentance through warning of punishment to come for being self-consumed.