Everything is possible.
Nobody can guarantee you anything for a infinite time.
Do you want to buy insurance?
No thanks:)
Just download the version of the wallet (
https://bitcoin.org/en/version-history) you need, then use dumpprivkey or maybe dumpwallet to get your private keys, and then use importprivkey in your updated client.
Thanks, but how will I be able to know which version of the wallet I need after those 2 years?
The privkey will pretty certainly never change in format any time soon, even if wallet implementations do. If it does, you should still be able to convert the privkey with little effort, keeping in mind that it'd be absolutely insane for the devs to not provide a conversion tool for old wallets (or allow both formats to be used) if they should make incompatible changes.
To answer your question, the level of risk is about on par with someone finding your privkey through brute-forcing.