Everyone on all sides of the G+ realnames controversy agrees that there are cases the present set of rules aren't handling well, even if they differ on which cases are the most important ones. Here's a modest proposal: let's not try solving all of them at once, if for no reason than that attempting that would lead us into endless and possibly unresolvable philosophical wrangles.
Instead, I suggest a less ambitious program of slicing off corner cases that can be solved at low cost first, and deferring the tougher ones until we can use that experience to revise our evaluations of cost/benefit. I have a particular one in mind.
There's a felt need out there for people to be able to at least claim long-term aliases or nicknames by which they are better known than by their legal names. Two exemplars that have come up often are Skud (aka Kirrily Roberts) and Lady Gaga (aka Stephanie Germanotta). And I'll admit I'd like to allow people to reference me as "ESR" if they wish.
These are transparent handles. They don't conceal anything; there is no intent in them to obscure identity or disclaim responsibility. There shouldn't be any ethical issue about supporting them for either anonymity advocates or transparency advocates.
I think G+ could solve this problem relatively easily. Here's how. Add a form to apply for an alias. Once the alias is registered, it would become usable as a + reference and discoverable by name search. Limit of three per customer to prevent spamming of the namespace. Well, N for some small N, anyway.
Aliases should be challengeable on grounds of non-uniqueness, though, so I couldn't claim "Eric" and Lady Gaga couldn't claim "Stephanie". They should also be challengeable on grounds of offensiveness, so we don't get Heywood Jablowme or SexyChic69. (I'm no prude, but vulgar handles lower the tone. Take those somewhere else.)
In general, nicknames should be considered a curated namespace rather than first-come-first-served. In case of challenge, the dispute gets bumped to a human to be decided by common-sense rules that Google can develop over time without having to specify in advance.
This does mean that famous people like Lady Gaga (or less famous ones like Skud and myself) would in some sense get preferential treatment. But I think this is what we all actually want out of such a system. Do we really want anyone who isn't Stephanie Germanotta to be able to claim "Lady Gaga" and keep it? The only sensible answer is "no" - and that means human judgment about the claimant's reputation will be required.
This proposal doesn't solve the hard problems about anonymity, nor the internationalization problems with single-word names and the like. It's not intended to. But by isolating one chunk of the anonymity/identity problem on G+, maybe it will reduce the heat and disputation around the others.