John Gill Commentary Luke 20:15

"And they cast him forth out of the vineyard, and killed him. What therefore will the lord of the vineyard do unto them?" — Luke 20:15 (ASV)

So they cast him out of the vineyard
Rejected him as the Messiah, even denied that he was of the Jewish nation; said he was a Samaritan, and delivered him to the Gentiles that were without, and were aliens from the commonwealth of Israel; and at last had him without their city, and put him to death, as follows:

and killed him ;
the Prince of life, the Lord of glory, and heir of all things; see (Acts 2:23Acts 2:36) (3:15) (5:30) (10:39)

what therefore shall the Lord of the vineyard do unto them ?
the husbandmen, the chief priests, elders, Scribes, and Pharisees; at whose solicitations the life of his Son, and heir, was taken away; by which he must be greatly provoked and incensed.