Depends. do you already have a regular PS4? If so, then just wait at this point as any PS4 models can play all PS4 games as far as I am aware, that is unless if you need an replacement and can find one for a decent price.
But if you're one of the few who never made the leap and is still hanging onto your PS3 after all these years, then unless if you want to venture into the PS4 era, then you should probably hang in there for just a little while longer.
Bottom line, should you get the PS5? Up to you, but my I offer you a word of advice? DON'T BUY IT IMMEDIATELY!!! ~WAIT~ for a bit BEFORE you make the purchase.
The reason why is because it would give you the opportunity to see if there's any issues that may come up. Because manufacturers can only do so much on testing the functionality of the devices, so it's up to the consumers to state online if there's any issues and such. Kind of like the Xbox 360, back when people started to buy that console, many thought it was going to be a decent console until almost half, if not more, of the people who initially bought it started to report the whole horrendous RROD issue, which was pretty common. That is the prime example on WHY YOU NEED TO WAIT FOR A BIT BEFORE YOU BUY ANY NEW CONSOLES!!!!!