They will need to rebook you into the same class of service as payed for, so if you had a business class ticket, you‘ll fly business class - unless you accept a voluntary downgrade to (premium) economy, e.g. because there are no free seats in business on some routing you want to take.

Eurowings/Germanwings not before mid/end July, Lufthansa mainline probably not before August.

Anyhow, for once i can see LH has good chance they will stop the strike action before the courts. UFO (the union) unilateral canceled the last framework contract after some internal scandal and disputes where the whole leadership needed to resign. The new interim union leaders thought it would be a good idea to put Germanwings and LH under pressure now and took a bold move by terminating the current framework contract and then calling for strike action. Probably to win favors with the union base and get elected as leadership team when those elections are due.

LH claims the current leadership team doesn’t have the authority to cancel contracts and renegotiate a deal. The union should get their act together and get back to normal formal process with setting up elections to nominate a new leadership, formulate demands for the next framework contract and then get back to the table to talk about it.

I’m usually not a big fan of Lufthansa management (not a fan of unions either...) but in this case, at least according to the information I got, I would side with lufthansa. Strike for higher salary is not supposed to be a tool for a interim leadership to win over the union base.