If Kisame manages to spit his water dome out before he gets blitzed and killed, Tobirama can easily create shadow clones, and have them all use water dragons and water jets (Suiton: Suidanha) to propel them in different directions and out of that large mass of water. Kisame's 1,000 sharks are all made out of water so they aren't swimming faster than the water dragons can underwater since they're all affected by fluid resistance. The key thing here is that Tobirama has a headstart; Kisame creates his sharks near himself and he is located at the epicenter of the dome. If the real Tobirama isn't able to get himself out first, he can teleport to a clone that does.
For those dicussing Gojō Kibaku Fuda, the 4th Databook strongly hints that he can use it without Edo Tensei:
- It says that he created this technique for the purpose of combining it with Edo Tensei; that doesn't at all imply that he is confined to using it with Edo Tensei only.
- If a live person can do it, then shadow clones can as well since they're just replicas of live people and they have been shown to be able to bleed and take damage without disappearing.
- Tobirama shows how the jutsu works
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(pay close attention to Tobirama in the top right panel). He
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and takes them out. Without ET, he probably has another means of providing the paper and marking them if he can use it alive, which is the real reason for the technique's DC, not the amount of paper the edos have.