It is not Art 1, Sec 23 of the state constitution yet. First, the election has to be certified. Once that happens, I don't know if the SoS has to do anything, but I would not be surprised. I would 110% not do anything currently illegal until that goes through at least.
Once it is official, there are a few different courses that can happen.
1. Somebody in the state legislature, probably with the concurrence of the MO AG, will decide that some of the existing firearm laws are in violation of the constitution. They will submit a bill to change that, and it will have to be signed by the governor, we all know the drill. I would not expect that before next year, since the legislature is out of session, and can't consider new business in the veto override session by statute.
2. City councils, with the concurrence of their City Attorney or MO AG, will decide that they don't want to fight the legal battle, and change their ordinances. I really suspect that's not going to happen. At least not initially.
3. Someone will get arrested for violating one of these anti-OC laws, and mount a defense based on the new Art 1. Sec 23. I suspect the city will then work to exhaust your funds. The good news is that the state is required to defend you. How that will work out in practice is yet to be seen. I would definitely have my own lawyer though. Then, the ordinance may be overturned, and other cities ordinances will fall more easily with precedent.
In any event, the only way to force the issue is to get arrested, and I'm not quite ready to take that for the team.
As far as Constitutional Carry goes, option 1 or 3 are the only ones possible, except you'd likely have the state playing both sides of the courtroom battle. That would be interesting.
It is not a law. It is now Art. I, Sec 23 of the state constitution.
The new wording affects current law. Smart city councils will be proactive and repeal their 21.750.3 OC bans, others will need to be sued and then forced to repeal 21.750.3 OC bans.
Essentially, "strict scrutiny" means that "shall not be questioned" will mean exactly what it says. Though, there will be resistance and court cases are likely. Are we a step closer to unrestricted OC? Maybe, but "unrestricted OC" will be closer to 571.107 (1 thru 17) restrictions than true "constitutional carry." Also, if the state don't want to get sued they will need to amend those because "shall not be questioned" means what it says.
I would hope that public buildings that we use on a daily basis, DMV, tax assessor, other bureaucratic offices, town/county council meetings, state rep/senate peanut gallery, will be made carry is OK, even if only CC.
We'll see.