Of course, the electoral system could be changed. Push comes to shove, an FPTP or something of the sort with gerrymandered districts could be used to minimize the non-Zionist representation. But, given the residential segregation, such gerrymandering would have to be pretty blatant. And, as the non-Jewish share of the electorate grows (for demographic reasons) the "problem" would get "worse".
Another "problem" with FPTP in that situation is that Arab turnout in elections is very low and many Arabs who have the ability to accept Israeli citizenship haven't (as discussed above). That makes it kind of like Northern Ireland, where the Unionists used to hold every seat because Catholics mostly boycotted the elections, but in the past several decades seats that were once safe unionist became safe nationalist, as Catholics became more politically active.
