The total value of US dollars in circulation steadily and rapidly increased during the 20th century as it become used as the worldwide currency in many aspects. The per-USD value was lowered (as explicitly intended) by increasing the money supply to ensure that there would be an inflationary, not deflationary regime - e.g. https://tradingeconomics.com/united-states/money-supply-m2 shows a nearly 50-fold increase of USD supply just since 1959.

If LTC gains widespread adoption and utility, the total value of all LTC in circulation will unavoidably have to increase; in essence, the total circulation value (supply * velocity * value) of a currency has to match, by definition, the total value of goods and services traded in that currency. Since LTC supply is limited by technical means and can't/won't be increased (like USD), this inevitably will mean a significant value increase of each LTC.