There are always dissidents, even if the top mining farms agree on hardfork and say 3% of the network doesn't.
The small miners will mine the old chain, because the difficulty will be low there once the big guys get out, and then slowly the miners will come back there because the diffuculty drop incentive as more and more support goes there.
Eventually it will settle at 50-50%, the supply of bitcoin doubles, and your money will be worth half as it was previously. Enjoy that...
Your 50-50% and the supply of bitcoin doubling is simply nonsence. After first halving, there were few who hard forked and continued mining blocks with 50 BTC reward. Where are they today? How popular is their chain ? And most importantly, did it even doubled the Bitcoin supply ?
If it was as simple as you describe it, Bitcoin would be already worth almost nothing as every hard fork from small group of people would create long lasting chain somehow mysteriously settling at equeal popularity and everytime reducting the Bitcoin market cap by half. How clever attack! Except it doesnt work this way...