Drupal - Which contributed modules are being moved into Drupal 8 core?

Modules brought into core

Entirely:

Breakpoint
CacheTags
Content Translation
Email (simple field, HTML5 validation only)
Entity API
Entity Reference
Entity view modes
File Entity
Link (simple field, HTML5 validation only)
Phone (simple field, HTML5 validation only)
Picture
Quick Edit
Transliteration
UUID
Views
RESTWS (Renamed to REST module)

Partially:

Admin Views (reworked)
CKEditor
CTools
Date (all except recurring dates)
Display Suite (view modes)
Internationalization
Migrate
Views Bulk Operations (reworked)

Removed

Blog (moved to contrib)
Dashboard (moved to contrib as Homebox)
Open ID
Overlay (fundamentally reworked to not provide an "overlay")
PHP Filter (moved to contrib)
Poll (moved to contrib)
Profile (Use Profile2 now)
Translation (replaced by Entity Translation)
Trigger (use Rules now)
Signature (functionality provided by User moved to contrib)
XML-RPC (moved to contrib)

Modules fundamentally changed by Drupal 8:

Deprecated (you won't need these anymore)

Admin
Administration Language
Bean
Boxes
Caption Filter
Computed Field
Ctools exportables
Fallback Language Negotiation
Field Hidden
Fieldable Panels Panes
Float Filter
Hidden Field Widgets
History
IMCE
Localization update
Localized Drupal Distribution
Menu Block
Menu Trails
Module Filter
Node Reference
Placeholder
Profile2
RSS permissions
Services
String overrides
Strongarm
Token
Transliteration
User Picture Field
User Reference
Vertical Tabs
Wysiwyg * (the module and everything related to it)

Reduced (these will have less work to do)

Backup and Migrate
Context
Custom Breadcrumbs
Features
Feeds
Menu Breadcrumb
Service Links
Rules
Views * (every module related to views)

The short answer is that Drupal is developed by the community, so it depends on what YOU (anyone reading this answer) add to Drupal 8.

I always use the Add jQuery UI elements to core issue as an example of how this process works. A few people had an idea, they posted some code, it was reviewed and debated, then added to Drupal 7 core.

Core contributions are by no means exclusive, so be bold! Start contributing.

It's not modules which are pulled into core, it's functionality. Functionality that might have been provided by contributed modules (and the code that was added to core might have been influenced by those modules but not necessarly that actual code is reused. For example fields, which was inspired by CCK but was a complete rewrite from scratch). And then these contrib modules don't need to be ported to the next core version.

That said, there is no roadmap in Drupal core development. So it is impossible at this point to answer your actual question.

The only thing that now exists are a number of so called core initiatives. That is an area where people are working together under the "lead" of the initiative owner to improve Drupal in a specific area. One of those is HTML5 (which might mean that a number of HTML5 related modules might not be necessary in D8) another is Web Services and Context (which means that for example the Context module will be unecessary and maybe parts of Panels). But all that is just speculation at this point. Because even though these initiatives exist, it is not set in stone that anything they're working on will be commited.

That is basically the two main tasks that Dries Buytaert (and to a certain degree co-maintainers, initiative owners, ...) are doing. They're talking about how Drupal could evolve and what could be done. And then finally Dries decides if a patch is commited or not.

In between, everything depends on if there are people who are interested in something and want to implement/improve/fix some part of Drupal core.