I didn't have access to the right book to properly take a look at what would happen to India in this scenario before , but obviously the changes would be huge. In general, timurs arrival caused the fragmentation of political authority in North India that allowed for regional centres to emerge in one of the most culturally productive ages of Indian history. Architecturally, the timurid style was irresistible to the regional sultanates and Hindu kingdoms throughout india, with its complex vaunting and domes and polychrome tiles. Timurs effect was also seen more generally throughout the world of Islam by definitively rejecting the Abbasid model of sultan who fights for Islam but has no right to define it or engage in religious disputes in exchange for the 15th and 16th century model where sultans were expected to be not just aesthetically accomplished (reflecting their complete spiritual perfection) but semi divine themselves. Timur popularised the title Sahib Qiran- lord of the auspicious conjunction. It's possibly pre Islamic and denotes the fact that this ruler has universal authority because their coming was foretold in the stars, they're a new Muhammad, or Ali or maybe even Allah made flesh as Shah Ismail claimed. Sultans are expected to be saints, manifestations of divine light, and saints could transcend the barrier and become sultans like the safavids. Without this introduction of cultic power into Islamic kingship, it might look a bit more similar to European kingship, where in religious matters, the authority of the king isnt worth much and he has to submit to the religious authority of a foreign power. Because of this, I think Islam will be a much less attractive to the kingdoms of Indonesia where kings are defined by personal religious charisma/ semi divinity so that region is less likely to be islamised.
Across the Islamic world, timurid customs set a glittering cultural standard that everyone was desperate to emulate- without it, perhaps even western Islam becomes more regionalised. Without timurid ideological basis for the rulers authority in religious matters, and without having that prestigious cultural model to emulate, perhaps even the ottomans become more romanophile than otl when they conquer Constantinople, as it gives them a greater basis for sultanic autocracy than the Abbasid model of sultan subservient to ulemma.
In Bengal, the Raja Ganesh coup led to him taking over the Bengal Sultanate and it was the threat of invasion from Jaunpur (a breakaway from Delhi after Timur wrecked the place) that contributed to his son committing to Islam and going so far as to be the first non Arab to claim the title caliph. Without this, what happens in Bengal? Would they be as scared of the decentralized far away military of Delhi as the local vital Jaunpur sultanate? They definitely wouldn't restore brahmanical style Hindu kingship, but there's potential for things like discarding Persian entirely for Bengali and adopting (which happened to an extent otl anyway, but if strengthened could work the scripts as well).
On the opposite side of the subcontinent, what's happening in Gujarat? Timurs invasion allowed it to set itself up as an independent Sultanate- but I think independence is likely anyway. Before Timur the region was dominated by merchant oligarchies based in cities who made ad hoc alliances with the pastoral chiefs who dominated the country. Timurs arrival allowed the formation of a court society based around a local darbar, and it was the sultan who came to dominate the pastoralist chiefs, form a standing army and navy (at an age where those concepts were barely present in the rest of India and Europe) . Without Timur do we get more of a merchant oligarchy style of government taking the initiative in handling their own defense arrangements?There's the possibility of them working in collective being able to use Gujarats intensifying agriculture and especially world famous textile production to throw off the reins of Delhi, but if they don't or if they split into competing regions and Gujarati doesn't emerge as the language of a particular state, is there any case for a specifically Gujarati identity forming?
In general, this period was incredibly important for the formation of the Gujarati language and ideas of Gujarat as a coherent region, so maybe without an independent Gujarati state, of if there are multiple city states the language never diverges from the language spoken in the Rajput states and a more consolidated western Hindi bloc forms in opposition to central Hindi in linguistic terms at least.
The linguistic effect of the fragmentation of sovereignty in this century has been described as a vernacular revolution, as the smaller states and their constituent chiefdoms moved en masse to patronising the vernaculars instead of almost entirely focusing on Sanskrit and Persian as the two prestige languages. With larger polities, does Braj bhasha achieve its later status or is the standard based on Delhi's speech? If Bengal can expand into the declining Tuglaq Delhi sultanate, do all eastern hindi languages get folded into Bengali?
Without the massive demand for military labour from the constantly competing smaller states making people from the eastern gangetic plain cross over to the west and form the emerging Rajput classes, do the Hindi languages diverge more?
If regional languages don't attain literary status are they more isolated from Persian, which would presumably remain the unparalleled language of state- without as well established literary standards of India's vernaculars, does Persian spread more through the masses, or are the regions where awadhi was cultivated as a prestige dialect be folded into a Bengali speaking zone without the jaunpur sultanate to nurture awadhi? Would the less regionally based tughlaq sultans be as willing to integrate Jains and brahmins and Vaishnava literati into their administrations or would court culture remain more isolated from India as a whole? It might emerge that Delhi's less Indic nature pushes the Bengal sultans to embrace their Indic nature more over time- already otl Bengal sultans ritually bathed every morning in water from the Ganga. Perhaps the same could happen with Kashmir, which otl saw demands for tribute from Timur leading to the destruction of four major temple complexes to use their gold as bullion, and the extreme taxing of brahmins to meet this tribute- without Timur maybe brahmins stay more socially relevant and the islamisation of Kashmir is halted. Otl, by the end of the 15th century, the language referred to as desi or native to Kashmir by a famous Kashmiri Hindu poet was Persian, so it's possible that Kashmir emerges as a majority Hindu Persian speaking sultanate, with Kashmiri itself relegated to only being spoken by the rural population.
