Are there any alternatives?

Yes, but not a lot. The Roccat Vulcan TKL and Cooler Master Cooler Master SK630 are both cheaper low-profile alternatives, though they lack wireless and use different switches. The G915 is fairly unique with its combination of switches and wireless technology, but there are boutique options that use the same switches with a wire.

　　

How long will it last?

Logitech’s GL switches are rated for 5o million actuations. Of course, the number of actuations depends on how often you use your keyboard. Assuming general use, the G915 will last several decades, and even then, it might still have a little life.

　　

Should you buy it?

Yes, but look for it on sale. The G915 has some obvious oversights, and it’s incompatible with most mechanical keyboard accessories. It’s a fantastic low-profile option, but Logitech is able to charge a high price given how few true competitors it has in this category.