"to purchase a Long Term Care policy. Will all of that be taxable?"

Which part? Is this what you are asking:

The cash value in the life insurance, for funds already tax before being paid in, were used to buy LTC. There is no tax on the life insurance funds, since they are likely less than what's been paid in all these years.

Or, are you asking:

The LTC will be paid out against qualifying costs. There is no tax on the payouts, and besides, they offset expense, anyway.

"since the annual deductible amount for LTC insurance"

Deductible? Or "Premium?"

"apparently paid in full"

In other words, there is no further premium for ongoing coverage? In general, a paid-in-full policy will generate interest that is used to cover the premiums. And if they don't cover that cost, you get a bill to pay. You'd have to know what this policy includes.

"how does the taxpayer get to deduct the rest on Schedule A....over a number of years?"

The rest of what? Deduct the Premium (they are not paying)? Or, the "rest" is the balance of their costs for care?

There are qualified and nonqualfied policies. Google:

what are qualified long-term care premiums

Remember that there are limits by age for LTC premium deductions. Remember that these products rely on basis, and at the end, nearly every participant has lost, not made, anything. The fees alone are ridiculous.