Thoughts on shorting Bitcoin

Really new to cryptocurrencies so this is a bunch of speculation...

So here i go,

Surely there will become a point where mining bitcoin does not become financially viable. At this point in time the value of bitcoin is likely to be overvalued. Once it is not viable to mine anymore and mining operations cease surely the whole system will collapse as the miners will not be there to process transactions. Hence rendering the whole system invalid and worthless?

So could someone predict the point which this will happen and take a short position prior to it?

I have probably made something so complex sound to simple but as I said I don't know a lot about bitcoin. So attack/reinforce/build on my points would loved to be enlightened.