See, here's the thing. There are precisely two effective infantry AV weapons: the AV turret, and lockon launchers. Both are effective because they're nearly impossible to avoid, virtually impossible to detect (literally so if fired from beyond render range, at least currently), and able to kill faster than tanks can get to cover. In other words, cheese. So either you've got tanks splatting infantry with impunity because C4 and mines do fuck-all to a tank that keeps a healthy distance, or you've got infantry cheesing tanks that can't retaliate. Why, exactly, is a weapon with higher TTK and less damage per shot a worse thing than the AV turret, especially when you'd actually need to AIM and LEAD if the tank isn't stationary? If something that takes 8 shots to kill you starts pinging you, you've got time to scram and get out of range/to cover. If an AV turret round/lockon rocket hits you and you aren't already at long range and right beside cover, you're almost certainly dead.
I'll reiterate: C4 is fucking useless against tanks. It takes two bricks to kill a Lightning, which requires a) 700 certs, b) lots of infantry resources to keep your stock up, c) you to get into melee range with them without being killed, which is pretty much only possible in bases and certain parts of the mountainous regions of Indar and Amerish. And if it's a MBT, oh joy, you just wasted a bunch of resources because they're just going to drive off and repair.
Mines are even worse, being roughly the size of an ESF, and requiring the enemy to somehow not manage to see the giant warning signs on the road before driving over them. That's assuming you can a) find a choke point where mines won't be inadvertently avoided and b) do so in a place and time where enemy vehicles actually might come that way. Otherwise they're just a shittier sort of C4 for Sundie-killing.
As for the blindfire launchers? Heh, sure. Good luck landing enough shots to kill on a tank that isn't braindead even at close range, much less sniping you from 800m away.
dumb fire launchers work fine, try popping around corners or ducking behind rocks, or whatever. No, you won't get the guys shelling the base from barely inside render range but they aren't being tremendously useful to their team either. It's a totally free starting weapon on a class that can respawn in a few seconds with no limits or costs, and it works great considering that's what it is.
C4 also works fine, I've killed LOTS of tanks with it as LA. 700 certs is a little expensive but not that much (the guy in the tank probably spent more then that on his tank). The infantry resource is annoying, but now that tanks cost more it's a good trade. Also, 2 bricks of c4 will 100% kill a MBT too so I don't know what you mean about him driving off to repair. If you think C4 is quote "fucking useless", you're doing it wrong, no you can't charge the front of a tank across an open field and expect to C4 it, but there's plenty of situations where you can fly over it and drop some or run up behind it (nobody uses radar, ever).
You also totally forgot base turrets, which are BRUTAL. They will shred any tanks have excellent range, unlimited ammo, and cost nothing (in fact you get certs for fixing them if they get blown up).
I agree mines were overnerfed. You can still use them sometimes if you find a road that twists behind a rock, or something, so they drive over them before they see them but mostly.. yeah. Old mines were too good because the render distance was so short you literally could not stop before you hit them even if you slammed the brakes the instant they rendered (and sometimes they sunk into the ground and never rendered at all). They fixed that.... and made them HUGE in the same patch for some reason.
As for the sniper thing, even if it takes 8 shots we don't need a team of 4 people being able to lock down an area and make it totally 100% invulnerable against all tanks (and if almost hitscan speed, libs galaxies and maybe even ESF) forever, or worse a team of 8 people coordinating to instagib tanks with no warning and no chance for retaliation ever. If you can't see how this is a terrible idea, I don't even know what else to say.
I'll say it again, tanks aren't a problem. It's tank zergs, but it's the zerg part of that not the tank part that's causing the problem, the tanks just make the problem somewhat worse.