My Trek 1000 is sooo much lighter without the wheels
I havent much knowlege but are the alexis wheels on the heavy side?
It seems that wheels are a very expensive part to buy seperatly.Is it worth it to spend lots on really good wheels and hubs and then swap them if I buy a better bike?
Thanks

Wheel make up about 25% of the bike's total weight, so I would say yes. And yes, keep them if they wil be compatible with your next bike to make an awesome machine.

I think hubs 10 speed hubs can have 8 speed cassette?

OP - It's been said many times here before: Good lightweight wheels are the best upgrade you can make to your bike - Plus the Alex rims don't have a very good reputation.

thank you

Not all 10-speed hubs can. The loose-bearing Shimano hubs (Tiagra - Dura Ace) can, but many other hubs are too narrow to take anything but 10-spd. I was unable to run 9-spd on a set of AC Sprint 350s, for example -- and I know the Dura-Ace wheelset has a 10-spd-only freehub body as well.

So I will ask my bike shop to supply me with a set of wheels that can use on my 8 speed but that are able to swap to a 10 speed if I ever upgrade?

Any 8 or 9 speed hub can take a 10-spd cassette. There's just an adapter ring/shim that comes with the 10-spd cassette to make it wide enough for the freehub (you can make a shim in a pinch with a manila folder).