The issue is that we are already maintaining 90%+ uptime on icyveins. At some point during tomb, provided we can stack haste properly, it will be an easy 100%. This can't happen from a developper point of view, fire and SP were already nerfed because they were scaling too hard.
Hence, it will be nerfed. That's almost a certainty. How it will be nerfed is the more interesting question.