LTC has been around for a very long time and all this time it has kept up a very high volume, a very healthy network, an active developer team, and a high price ($4+ for the most part).
i don't see why this has to change. LTC will continue as it was if not better with all the additions.
LTC-BTC price is going down while LTC-USD is rising. so far 0.017BTC and this shows this coin has some potential for rise. if you have some LTC and wanted BTC you should have sold when it was above 0.02BTC before the bitcoin rally. now it is late and unless bitcoin goes above $3000 i don't think LTC-BTC will go any lower.
as for selling LTC to buy ETH, that is your decision. i would not do it at the moment with the recent huge ETH hack there is a lot of dumping going on.