Agent here;
Buy to Let is still viable, as is flipping - it's a case of assessing the risks and finding the deals - there will always, always, always be deals - you just have to know where to look.
Can't assess the £50k/10% yield thing without knowing the area, location, likely rental, average capital value for the area, your mortgage, refurb costs etc....lots to think about.
You are wise to consider tax changes and interest rates. I attended a lecture recently where a mortgage broker advised everyone to pull all their cash (equity) out of their investments so that they could buy more properties. Great idea while interest rates are low, but what happens when you're living on nothing but borrowed funds, your capital growth falls below interest rates and then you try to sell.......at the same time as everyone else has the same idea.
Couldn't see the benefit to that, other than the mortgage broker getting richer from the short sightedness of a room full of Landlords.
the tax changes will make things a little more difficult but it's not that Landlords are getting taxed more than usual, they won't be getting the benefit of being taxed less for the income anymore (rate relief has gone) - you can still work a way round it if you have multiple properties and put them through a company and run your portfolio as a business, but if it's just one BTL just factor the tax into your breakdown before purchase, and ensure you know how to extract maximum value from your investment once you've got it.
Any half decent local letting agent should know most of this. Try and find somebody who has at least done some kind of training or qualification in this stuff otherwise they're as much use as a chocolate teapot to you when it goes pear shaped.