I'll be posting my predictions for the 2021 Assam Assembly Elections here.

Grouping the Assembly segments from each Lok Sabha constituency here, since many overlap districts.

Basic demographic breakup

Assamese Hindus ~40%
Assamese Muslims ~8%

Bengali Hindus ~11%
Bengali Muslims ~26%

Other Hindus ~10%
Remaining ~5%

Vote breakup in 2019

Hindus 70% NDA, 16% UPA, 14% Others

Muslims 70% UPA, 7% NDA, 20% AIUDF, 3% Others

Upper Caste 74% NDA, 13% UPA, 12% Other

OBC 60% NDA, 22% UPA, 18% Others

SC 66% NDA, 9% UPA, 26% Others

ST 86% NDA, 7% UPA, 7% Others

Assamese Hindus opposed to CAA (75%)
NDA 56%, UPA 28%, Others 16%

Assamese Hindus supportive of CAA (25%)
NDA 88%, UPA 4%, Others 8%

NDA received 64% of the Assamese Hindu votes in 2019 while UPA received mere 22%.

This mean that over half of Congress' voteshare in 2019 was from Miyas alone.

Bengali Muslims 70%
Assamese Muslims 66%
Assamese Hindus 22%
Other Hindus 4.5%

AIUDF fielded candidates only in Dhubri, Barpeta and Karimganj, so there was complete Muslim consolidation elsewhere.

With the AIUDF-Congress alliance, you will see a complete Miya consolidation behind UPA (26%) while the Assamese Hindu votes either shift to NDA or Others like AJP, Raijor Dal, etc. If Assamese Muslims votes also get pulled similarly, UPA will have it harder.

Bulk of the Hindu votes that UPA got in 2019 came from Upper Assam from communities like the tea tribes, Ahoms, Koch Rajbongshis, etc.

If Congress loses even a significant chunk of these votes, many seats in Upper Assam will flip to NDA.

I'll be dividing the state into 3 groups (Barak Valley, Lower Assam and Upper Assam)

I'm clubbing the central hill districts with Upper Assam here for sake of convenience.

Barak Valley (Karimganj, Silchar)
NDA - Ratabari, Patharkandi, Silchar, Dholai, Udharbind, Lakhipur

Barkhola and Katlicherra are v close to call, but I'm giving it to UPA.

NDA 6
UPA 9

Lower Assam (Dhubri, Kokrajhar, Barpeta, Gauhati, Mangaldoi, Nagaon)

UPA is going to make a clean sweep in Dhubri and Barpeta barring Bongaigaon, Patacharkuchi and Dharmapur.

They will also take Boko, Chaygaon, Mangaldoi, Dalgaon while Hajo and Barkhetry are uncertain

In Nagaon, UPA will retain their bastions of Laharighat and Jamunamukh while Raha is 50:50 for both sides.

In Kokrajhar, Muslims will move behind alliance while Bodos will split between UPPL and BPF. Non-Bodo Hindus will consolidate behind BJP.

UPA 26
NDA 33

Upper Assam

NDA will sweep Autonomous District, Tezpur and Dibrugarh.

Naoboicha is 54% Hindu, so it will stay with UPA unless there is massive Hindu consolidation in the seat.

Sibsagar will likely flip from UPA to NDA this time because of Others.

Titabar and Golaghat remain to be seen, but I'm giving them to UPA for now.

Dhing, Batadroba, Rupohihat and Samaguri go to UPA

UPA 8
NDA 44

Overall

NDA 83
UPA 43

Total in 2016
NDA 86
UPA 39
Other 1

I'm including Sibsagar and Raha for UPA here, but I have a feeling both will flip to NDA.