This is the kind of thinking they're hoping for. Chances are many will comply so they can continue their hobby activities. They'll think "well I can do this registration thing but if they come for them I'll say I sold them blah blah." The timespan between registration and confiscation will be short. It would be foolish for ANYONE to register but when things like this happen we become our own worst enemies.
I doubt that horrible bill will even make it out of the Senate in it's original form. If it does there is still the House to block it. But if something passes that includes ANY form of registration then our gun hobby is essentially over and the stuff gets put away for what comes next. If you register then they know and you know damned well you're not going to blast the officers that come for them. Nobody should comply, period. We draw the line here and stick to it. That is our only hope.