I have this MacArthur excerpt too concerning the passage which I thought might be helpful. Gotta go right now, but I'll be back later so please let me know if this answers your question(s). --David
A tower, perhaps associated with the construction of the Roman aqueduct, fell and killed eighteen people. That tragic calamity did not happen to them because those folks were the dregs of Jerusalem’s society, since Jesus specifically declared that they were not worse culprits (lit., “debtors”; i.e., to God for violating His law) than all the other men who lived in Jerusalem. This second illustration reinforced the Lord’s point that natural calamity is not simply God's way of singling out particularly evil people for judgment.
......but unless you repent, you will all likewise perish (13:3b, 5b)
This twice-repeated phrase introduces the inevitable calamity that everyone faces. That most severe judgment, from which no one escapes, is that unless people repent, when they die they will all likewise (not in the same manner, but with the same certainty) perish eternally (cf. Heb. 9:27). In the terms of the Lord’s analogy, they need to settle their case before they face the divine judge and it is too late (see the exposition of 12:58–59 in the previous chapter of this volume). Most of the Jewish people were caught up in a works-righteousness system that forced people to view themselves as good based on selective and superficial perception. Consequently, they refused to see themselves as sinners and therefore rejected (Matt. 11:20) Jesus’ call for them to repent (Matt. 4:17), just as they had John the Baptist’s before Him (Matt. 3:2). Ultimately, it was because Jesus rejected the Jewish people’s hypocritical self-righteousness, categorized them as spiritually blind and impoverished, and boldly confronted their need for repentance that they plotted to murder Him. Luke 11-17 MacArthur New Testament Commentary