The claim/warning that Hylines are bred to be 'sprinters" and burn out by two years is not true in my experience. Properly cared for most chickens will lay well beyond 4 years even more although you may not expect eggs every day from the older hens but they will still produce their fair share of eggs every year.
Where the Hyline and other commercial "hybrid" breeds get this reputation from is that they are developed to mature earlier than the heritage and other breeds and are often at around 6 months or when they mature and reach point of lay, put into the crammed battery cages and induced to lay twice a day using artificial light and dimmers etc to make their bodies think there are two days in one. It's a misconception that grows from the industry need to make quick and better profits and the consumer demand for more and cheaper eggs.
However no hen can sustain this for more than six months, so at around 12 months they are moved on to make way for the next generation of pullets coming through. Some are sold and can continue producing an egg a day for quite a while after slowly diminishing as they get older in baryard, free range, backyard environments and the like. I suspect some may end up on the dinner table or as pet food. Some battery farms keep some to produce larger eggs to satisfy a segment of the market.
I often get these hens from a local poultry farm at 12 months for about a third of the price of a Hyline point of lay pullet and they lay for many years afterwards. They are a very tame, placid good natured chicken and easy to manage.
The term hybrid is a misnomer as they are not really hybrids at all but crossbreds. Hybrids are a cross between two separate species of a diferent genus from each other and are invariably infertile. Most chicken breeds are of the same genus and the Hyline, Shaver, Ross Brown hens etc can run with a rooster of any breed and will produce fertile crossbred eggs. I have done so myself and know other people who have also done the same. I have also seen people advertise chickens with commercial "hybrid" parents in their breeding.
How they are cared for and managed is more important than any preconception or misconception as to whether they are so called 'sprinters' or 'stayers'. I have bred and exhibited many breeds from Pekin bantams to Minorcas, Orpingtons Leghorns etc in the past, as well as keeping some commercial crossbreeds and they will all produce well if properly managed. Admittedly some breeds will produce better as layers and some heavier breeds will make better eating birds than others but most will still produce their share of eggs whether a specialist laying breed/crossbreed or heavier meat breed.
The exception would be bantams which still retain stronger natural breeding instincts and lay enough for a clutch big enough to incubate and then go broody and hatch them out and rear them bfore starting to lay again. There are some heritage breeds that also do this.