If in future difficulties of every crypto currency start rising then it's means new and more heavy hardware will be needed??
That is more likely the case But with increasing Difficulty there will be a increase in price as well. And also it is gonna take months before it all happens. But it will only happen if the Scrypt ASICS come out. That I highly doubt even exist. Also we already have 70-80% miners that switched from BTC after ASICS came so until there are no ASICS for Scrypt we are good to go.