There seems to be a lot of confusion on this thread about what salary sacrifice actually is. To be clear - at the moment when you or your employer make contributions to any qualifying pension scheme, they get tax relief (for you or your employer). What happens with salary sacrifice is that instead of you paying contributions into the scheme you “sacrifice” some of your salary and the employer makes a pension contribution instead. Since your salary is lower, NI contributions are lower.
There has been a fair bit of speculation that this sort of salary sacrifice arrangement might be targeted in the budget. Not sure how they could actually do this though. And, as previous posters have said, it’s the NI savings that would be removed only.
Especially for basic rate tax payers, there is no suggestion that the current tax relief on pensions contributions is going to be taken away. There is always speculation that higher rate tax relief might go, and very high earners already have their pension tax relief limited to £10k per year.