The best replacement for upnp is dlna.

The best alternatives to upnp are rated as following:
★★★★★  dlna
★★★★  port forwarding
★★★  smb
★★★  dmz
★★  nat-pmp
★★  nfs
★  nat-pmp utorrent
★  bonjour
★  samba
★  dmz ps3
★  nfs xbmc
★  mdns
  nat pmp
  zeroconf
  port forward
  enable
  daap
  dnla
  snmp
  dmz xbox

Your alternative for upnp is not listed? Suggest!
Speaking about upnp, one probably shouldn't forget about dmz.

Other search terms related to upnp and their ratings are:
★★★★★ dmz
★★★★★ port forwarding
★★ xbox live
★ skype
You have in mind a companion for upnp and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of upnp in all years. Click on graph for more.
upnp
dlna
port forwarding