In an attempt to clarify the previous post and answer your question let me add;

27 inch wheels were once the standard for high performance and other adult bikes. Somewhere around the mid to late 80's the transition to 700c took place. 700c is now the standard.
There are tons of 27" wheels out there and you can still get rims and spokes. Tire choice is probably the greatest limitation. 27" tires are still around but choices are limited, especially at the high end.

If your 27" wheels are in good shape, don't worry about it. If they aren't in good shape then you have a few decisions to make.
One option may be a new bike but it certainly isn't necessary. There are plenty of vintage high performance bikes still rolling on 27" wheels and tires.