My parent's have been landlords for 30 years, only the one BTL property. Had the same tenants in it for the last 15 years. Always charged below market rent, and never increased it during the last tenancy, so the rent was less than half current market rents for the area. The mortgage was paid off years ago, and the low rent still covered all the other overheads. Tenant was good, fairly easy going, low stress, generally looked after the place. But my parents have decided to evict them and sell up. Too much bureaucracy and overheads etc coming in (local authority is now requiring licensing for all rental properties, at a hefty cost).
This is the reality - all the 'legacy' cheaper tenancies are at risk, landlords cost go up, so rents will go up. Driving out the small time independent landlords who have low overheads and typically offer lower rents, meanwhile big foreign investment funds are buying up UK housing stock as fast as they can. And they are profit driven, so rents will be top whack.
My parent's tenants have now moved out, quite upset that they're in a worse property, with a higher rent. No idea how they've managed that even, since they wouldn't pass most landlords affordability checks, and never even asked my parent's for a reference (which would have been good, so no reason not ask if they needed one). Strongly suspect they've ended up in some slum tenancy with a dodgy landlord.
Meanwhile the house has sold (STC) and BTL investors were fighting over it, private purchasers couldn't or wouldn't compete. I expect the next tenant in that house will be paying twice as much.
Lose lose all round, except for the revenue, since there's going to be a substantial cgt bill.
Anyone who thinks this incoming legislation is going to be good for renters is deluded.