You can take any aircraft and "dumb it down" weight and range-wise. My legacy airline in the US had 8 777's and 8 767-300's configured with lots of seats for Hawaii flying (4.5-8 hours). Very low MTOW and the engines were derated. The bean-counters said it saved maintenance money. Our 757's originally had a MTOW of only 210,000 pounds for the same reason - they didn't plan on flying them very far. They did later increase the MTOW - twice, when they wanted to fly them farther.
There is no single replacement for a 757. It was a great plane. Gobs of power, big wing, low take off and landing speeds, decent range. 321's and 737-900ER's only fly about 75% as far, and you need a lot of runway, preferably at sea level. BUT. That covers probably 90% of the flights a 757 normally operates.