The text and discussion of the Washington State Measure can be found here:
https://ballotpedia.org/Washington_...ship_and_Purchase_Requirements_Measure_(2018)
There are storage requirements, safety tests, all placed to make it a burden to exercise a Constitutional right.
In terms of predicting the future, I recently read that there have been 307 mass shootings in the last 311 days. Constitution or not, if a democratic form of Government feels there is a real and present danger, and even people feel strongly on the topic, the body politic will eliminate that danger. Democracies can be very illiberal against things they feel are a threat.
I do believe that there will be more semi auto bans, then followed by bans on weapons with multi round capacity, and it will go on till all weapons are banned or forbidden. Just take a look at the knife bans in the United Kingdom, and China. The Brits have these slogans :
"Bin a knife and save a life".
When those bans come, you will have to decide to obey, or be crushed. I recommend leaving early adopter states and live in those states that are more freedom loving, gun friendly states.