I cant think any ways that would make our bitcoins more anonymous rather than on using mixers. Making a decentralized one would be really hard and we dont have no choice if government would took down those mixers out there because as mentioned above it do being used on terrorism and other illegal stuffs,
You didn't understand me as i see. I'm explain some technical staff here:
In mixer there one server where all money coming and then server mixing them by making thosands transaction in it's own network (in short). Centralized serves is a point, where mixing take place. How do you wan't to do it without this point? You can't make such servise. Only that you can do it's to change all bitcoin network, to make possibility of mixing money through customers wallets (this scheme already exists in DASH) But it makes bitcoin much slower cause nodes must be provide also this process.