while i personally believe that "fixing" balance issues before we know they exist is a bad idea, and just as likely to cause balance issues, I do see a few options. Class strength and population may actually work out to the vague asymmetrical balance concept the devs have proposed, and any changes for the sole purpose of balance need to wait till after populations have settled.

Pikko server could allow for artificial balancing based on the number and type of players in a single cluster - Im against this

"random" tyranid invasions to throw off a powerful faction or offensive - still artificial, still against it

incentivizing alliance members to turn on each other - neat, but should be a player action not a "moderator" action

I dont really see a way to control populations and stay true to the player driven vision of the game. I see it working itself out eg. the eldar are getting pwned by space marines so the council works out an alliance with chaos while simultaneously working out a cease fire with orks by ceding a promethium refinery to them. Wait for the right moment and then backstab everybody.

The more I think about it, the less I see a POTENTIAL problem. Besides, I love being the underdog.

I'm all for the tyranids attacking the largest factions. Alliances might be a better idea, but that does introduce other balance issues (such as certain clans grouping up across factions and beating down one group). So overall I like the idea of balance keeping tyranids (which will probably become a meme).

Maybe the Tyranids will be an unstoppable swarm that annihilates any faction that achieves total dominance. Say the Space Marines control 3/4 of the world, of course the % being arbitrary here, which then prompts a Tyranid invasion, full of everything you can think of, including Genestealers, a Space Marine equivalent.

These Tyranids will basically reset your faction if you don't have a proper plan to deal with them when they arrive. You would have to raid plan, and set up armies and defenses at various locations. Scouts will be utilized to report (maybe even a global report) what is where, and then you can allocate your armies accordingly.

If you fail, all your conquests are lost, leaving you vulnerable, and at a position where you must recapture your 'capital' in order to resume the 'crusade'. If you succeed, then your faction will be rewarded with something permanent. Perhaps the addition of a new class type (balanced, in terms of cost, etc.), such as Grey Knights, Chaos Sorcerers, Flash Gitz, etc. Maybe something more like titles or badges that say or denote 'World Conquerer'. The other factions will then receive a passive bonus as well, perhaps tipping the balance into their favor, or prompting pop. distribution to try a different race.

I would rather not have the Tyrranids do all my work for me, i like the idea much more of having an army of under equipped fanboys running towards the now very well equiped, if undermanned, armies to resist them. The space marines have a long overdue part of being the villains.