Hi Drees,

I've created a topic about this here: https://www.odoo.com/forum/help-1/question/how-long-will-the-odoo-v7-api-stay-available-will-it-be-removed-in-odoo-9-86441

To quote my answer from my topic:

 There has been a discussion about this on the official Odoo Experience (2015) and the compatibility with the V7 API will remain in Odoo 9. This means you will be able to use both the V7 and V8 API in both Odoo 8 and Odoo 9.

The exact moment when the support for the V7 API will be removed isn't decided yet and will depend on how fast Odoo itself changes everything to the new API and how fast the partners do this. It might even be the case that Odoo 10 will still support the old API!
Note: There hasn't been any official statement about this, besides in the Odoo Experience presentation about 'Ask Me Anything'. If the video from this presentation comes online I will add a link here that confirms this.

By the way, please use the search functions and/or Google.. I've already replied to two almost identical topics about this. You would've found this with one Google search.

Hi Drees,

Odoo V8 API will works for sure. On my tests I've use old V7 API and it works too, but since we are talking about a development version no one can guarantee compatibility, especially now that they don't share the latest bits of code. I strongly recommend to migrate your code to (at least) V8 API: the more you'll wait, the more likely V7 API will not be supported anymore.