Will this likely be landing in Chrome 67?

It is a possibility.

Unfortunately, still not enabled by default in chrome 68 dev.

Current plan is to re-enable post M67 launch via Finch, pending strong enough stability signals on site-isolation.
This is to avoid whiplashing the API on and off if site-isolation doesn't stick.

How does site-isolation permit this? Any chance site isolation is to be eanbled in Chrome 69?

Also is there a site isolation enablement ticket that can be linked? I did some searching but there were a lot of results & it was hard for me to filter through them with confidence.

Site isolation enforces a process boundary for origins, which mitigates a certain class of vulnerabilities related to Spectre.

As for timing please see comment #5.

#7: For more information on Site Isolation and side-channel attacks, and how `SharedArrayBuffer` is involved, please see https://chromium.googlesource.com/chromium/src/+/master/docs/security/side-channel-threat-model.md#Site-Isolation. We are hoping to leave Site Isolation on by default in Chrome 67.

Site Isolation is now on for all desktop platforms, and SharedArrayBuffer is now re-enabled on all channels for those same platforms. When Site Isolation ships on Android, SAB can be re-enabled there too.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4dbb4407b8a64dd9463ae34b1e9c19475acc1128

commit 4dbb4407b8a64dd9463ae34b1e9c19475acc1128
Author: Ben Smith <binji@chromium.org>
Date: Thu Aug 16 00:20:30 2018

Enable SharedArrayBuffer by default on non-android

It is currently enabled via finch for these platforms on 67+.

Bug:  chromium:821270 
Change-Id: Id402c71a8b9d108bbe0d8bca7fc585aff201241a
Reviewed-on: https://chromium-review.googlesource.com/1159358
Reviewed-by: Ojan Vafai <ojan@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Ben Smith <binji@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583458}
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/content/public/common/content_features.cc
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/TestExpectations
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[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/http/tests/origin_trials/webexposed/animationworklet-origin-trial-interfaces-worklet-scope-expected.txt
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/http/tests/push_messaging/resources/pushmessagedata-worker.js
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/http/tests/websocket/send-arraybufferview-expected.txt
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/global-interface-listing-paint-worklet-expected.txt
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/crypto/random-values-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/crypto/subtle/importKey-badParameters-expected.txt
[rename] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/external/wpt/html/infrastructure/safe-passing-of-structured-data/shared-array-buffers/nested-worker-success-dedicatedworker-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/css/fontface-arraybuffer-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/dom/geometry-interfaces-dom-matrix-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/events/constructors/midi-message-event-constructor-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/files/blob-constructor-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/peerconnection/RTCPeerConnection-datachannel-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/workers/worker-atomics-wait-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/fast/workers/worker-sharedarraybuffer-transfer-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/http/tests/origin_trials/webexposed/animationworklet-origin-trial-interfaces-worklet-scope-expected.txt
[add] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/http/tests/websocket/send-arraybufferview-expected.txt
[rename] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/android/http/tests/worklet/webexposed/global-interface-listing-paint-worklet-expected.txt
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[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/mac/virtual/stable/webexposed/global-interface-listing-platform-specific-expected.txt
[modify] https://crrev.com/4dbb4407b8a64dd9463ae34b1e9c19475acc1128/third_party/WebKit/LayoutTests/platform/win/virtual/stable/webexposed/global-interface-listing-platform-specific-expected.txt
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