Filing Form 5500-EZ if the value goes down

If I file Form 5500-EZ now, does that obligate me to file subsequent 5500-EZ forms for the following years even if the total plan assets are below 250k?

No. Form 5500-EZ is only required if the total plan value is $250,000 or above, as of the end of the plan year.

Filing the form is not required if the total plan value is below $250,000 as of the end of the plan year, even if the form has been filed for the previous year.

The IRS instructions for Form 5500-EZ note:

You do not have to file Form 5500-EZ for the 2025 plan year for a one-participant plan if the total of the plan's assets and the assets of all other one-participant plans maintained by the employer at the end of the 2025 plan year does not exceed $250,000, unless 2025 is the final plan year of the plan.

Form 5500-EZ Instructions