The best replacement for profibus is modbus.

The best alternatives to profibus are rated as following:
★★★★★  modbus
★★★★  fieldbus
★★★★  profinet
★★★★  devicenet
★★★  foundation fieldbus
★★★  hart
★★  rs485
★  ethercat
★  mpi
★  canopen
  canbus
  controlnet
  interbus
  rs-485
  can bus

Your alternative for profibus is not listed? Suggest!
Speaking about profibus, one probably shouldn't forget about gsd file.

Other search terms related to profibus and their ratings are:
★★★★★ gsd file
★★★★ controllogix
★★★ compactlogix
You have in mind a companion for profibus and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of profibus in all years. Click on graph for more.
profibus
modbus
fieldbus