What are my chances of making E-7 in Intel after reclassifying (Logistics) at E-6? Will reclassifying delay or create obstacles to promotion?

Promotion depends on two things:
What you control: your performance and potential in the new MOS (NCOERS)
What you don't control: E7 vacancies in whatever your new MOS is (you have tagged both HUMINT and SIGINT here)

Realistically, for FY26, with less than a year in your new MOS, you won't be considered Most Qualified among your peers who will have an average of 12 years in that MOS.
You are probably looking at promotion after 2-3 years in your new MOS.

So, here's where you have a career decision to make:
In order to progress through the ranks on schedule, stick with your MOS, or go warrant in logistics.
Or
If the job, being MI instead of LOG is more important than staying on your current promotion track, then reclass. Liking what you do for a living can be more important than promoting faster.

It's gonna be a 50/50 really. What will be one of the main factors is how soon you'd be done with the new MOS course and when the Board will convene that you'd be look at.

Honestly, I recommend you pose this question to HRC at their SNCO promotions department. Here is their email

[login to see]

Regardless of MOS you have to demonstrate you are proficient in your job field operationally and as a leader. If you are lateral moving this late in the game you will be putting your self at a clear disadvantage in regards to the FY2026 board but if that is what you want for your career that is your choice to make. But there will be some clear advantages and some clear hurdles to this choice. Know that going in. It's possible to do it and thrive but it's also possible to go in and struggle. That's on you and your ability to make it work.

Personally, I have a bit of heartburn when it comes to transitioning into Intel. It isn't your fault. I was a sergeant in Germany in the early '90s. Desert Storm came and went. Big Army decided that it had too many Soldiers. So, it offered an early-out.
98C (My MOS - Signals Intelligence Analyst) led the way. They left in droves. Then, the Army decided that it didn't have enough 98Cs. So, it gave Soldiers in other MOSs $15,000 to $25,000 to convert. It was called the Bear Program. Now, I was working for a no-experience Intel Staff Sergeant and I couldn't get promoted because there were now more than enough 98C-30/40.
They had no idea what they were doing, but they were there. Taking up space.
So, I went to OCS. I couldn't get E-6, but I could get O-1.
Ironic isn't it?
Anyway, back to your original question. I don't think that the Army or the promotion boards look necessarily at your Intel history for further promotion. It looks at your potential (or at least it should).
What do you want to do for the next nine years? Intel or logistics? That is where you should focus. If a change in MOS delays your promotion a year or two, but you want Intel, then take the lumps and move on with your career.
I'm not sure it this is useful, just my perspective. Best of luck regardless of what you choose. Both options have possibilities after the Army.

It depends. If you change MOSs, you'll have an experience deficit relative to your new peers. IF that new MOS has a substantially higher promotion rate than your old MOS, that may offset. But I wouldn't expect to be promoted in 2026 if you reclass in 2025. You'll have no performance record in your new job.