Official story: NS1 was shut down. Putin acknowledged repairs needed to Seimens' made equipment, impossible due to sanctions. Putin accused Europe of non-payment for LNG since they refused to pay in rubles. NS1 shut down. But, he keeps the pipe pressurized so that if he wants to turn the gas back on, he can to keep promises. This gives him leverage at the negotiating table, seems smart.

If that is true, what is leaking now is not new flow, but simply water backfilling the space where the gas is now in the pipelines. The bubbles will eventually stop once the ~3 million cubic meters of methane leaks out of the two pipelines.

If there is new flow, then we've got a deeper discussion because the official story was a lie in some way, and we can't anticipate much of anything without more information.

As for the collapse theory, it's a steel pipe surrounded by concrete that is designed to carry high pressure gas. I'm fairly certain it's engineered to handle the external pressure of the water. Additionally, once the pipeline is filled with sea water after the breach, the internal and external pressure equalizes, and you don't have to worry about further damage to the walls.

Source: https://www.wermac.org/nordstream/nordstream_part1.html