One thing that becomes apparent when you look at the history of technology is how common having two different technologies force each other to develop is.
The best example of this is how during the middle ages both armor and weapons improved. Over the centuries this meant that there were times where having the best armor made you all but untouchable, and other times when a really good weapon could go through any armor you would face.
This is a good reason to have a technology be developed, or to keep being developed.
One area that I think is underdeveloped in Science Fiction is the effect of practical sexbots.
By practical I mean that they can, for most people most of the time, replace women/men for sex and companionship. I don’t just mean the obvious, but also being able to hold simple conversations.
Granted there will be some people who would never settle for a bot, but how good would they have to be until they change things in ways both profound and subtle?
How many resources and time are spent by men and women to attract the other? What if you could get your dream girl/guy for one month of pay? Would you push yourself as hard at work or in life in general?
The interesting thing about this is that making them is a engineering problem only. It’s going to be a while before you see them in Walmart, but we don’t need any big breakthroughs. We just a lot of time and effort. I mean it’s not like there would be a problem convincing people that it would be a good return on investment.
One thing I have seen a few times is a main character in a book being the first to do something that should have been done well before hand.
For example, if I was writing a book about the invention of a replicator I would expect that it would take about a week for someone to note the many ways it can be used as a weapon. Or use it to make drugs. Or for that matter to have it create an explosive that would be so unstable it normally could not be moved, therefor used.
If your character is the first person to do something, think about WHY this is the case. Would they really be the first ones?
Technology, by itself, will not make your world feel alien. We live in a world where technology changes every day, waking up to new technology is normal, to make a world feel alien you need more.
The first thing you could do would be to get rid of a taboo. However be careful to understand both the logical and emotional reasons for the taboo existing before you do this. Taboos have far reaching consequences, make sure to not just change the surface level effects.
For example, the nudity taboo. One of the consequences of getting rid of it could be that our standards of beauty might change because we no longer can present a front that is anything but honest. I might be tempted to have this stem from a belief that honestly is important. If that was the case makeup could be seen the same way.
The next, as you might have guessed, is adding a taboo. This would be more tricky because you have to invent the reason for the taboo to exist, plot backwards from there to make it logical then plot forward for all the effects it would have .
In a classic by Heinlein, The Puppet Masters, one of the major plot points is that the only way to know that someone is not controlled by an alien is to see them naked. To wear clothing (more then a set of VERY short shorts) is to ask for a bullet to the head from a vigilante. Trying to talk congress into this goes about as well as you would think it would.
Even after the aliens are beaten this could not change because even if the US is clear, the rest of the world is not.
If you were to write a book set 100 years after the end of that book I would expect to see profound changes.