What you are describing is one of the many ways I use Lightroom myself. It can be used for archiving photos long term. However, keep in mind that these photos will live in the cloud, and as such you will need to pay for that storage for the duration of your "long term" archive. So long as you are OK with paying for this during the time of your archiving, it would work well.
However, I would suggest you also look at and assess the use of local storage systems (NAS, External Hard Drive, etc.) if archiving is the only reason you are looking at LR. LR, and it's accompanying creative cloud subscription, is a very powerful tool for editing and syncing your photos, so some of that power would go in-used if your only use case is as a storage system for archiving.
I hope this helps and please don't hesitate to post additional questions in the event I mis-understood your question.