The best replacement for ipv6 is ipv4.

The best alternatives to ipv6 are rated as following:
★★★★★  ipv4
★★  nat
★★  ipv4 header
★★  ipv4 security
★  ipv5
★  ipv4 speed
★  ipv4 number of addresses
★  mac address
★  tcp ip
  ipv4 differences
  ipv4 should i use
  tcp ipv4
  ipv4 faster
  ipv4 pdf
  clnp
  ipv4 protocol
  ipv4 nat
  v4
  ipv4 connectivity
  ipv4 ppt

Your alternative for ipv6 is not listed? Suggest!
Speaking about ipv6, one probably shouldn't forget about ipsec.

Other search terms related to ipv6 and their ratings are:
★★★★★ ipsec
★★★★★ ipv4
★★★★★ nat
★★★ dhcp
★★ eigrp
★ mpls
★ bgp
ospf
ifconfig
You have in mind a companion for ipv6 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ipv6 in all years. Click on graph for more.
ipv6
ipv4
nat